I have no knowledge of the oil pump and related shaft concerns, but I can speak to the exh crossover concerns.
When we bought our '66 Newport, it had 7100 miles on it. As I was learning about cars at that time in my life, I was paying attention to the complete vehicle. How it was put together, how it operated, AND I read the complete owner's manual. Tempering that with the 1966 MOTOR Manual I had bought (and similarly read cover-to-cover).
After a year or so, I noticed that the heat riser valve was stuck in the half-open position. The car seemed to operate "as new" with it like that. Efforts to free it up with the recommended solvent did not really help. But it seemed to not hurt anything, so that's where it stayed, for years. Everything operated "as designed", as to the choke working and such. No problems with engine power and such. It would still run 90mph in 2nd gear (2.76 axle ratio, 383 2bbl Stromberg WWWC3).
In reading many car magazines and such, I had read of some owner complaints about heat riser valves rattling and making noise. I found that curious as most of them were stuck, from what I could tell (as I also liked to hang out at the Gulf station, when Gulf was the real, older Gulf Oil Company).
That 1/2 open heat riser kind of bothered me. It HAD to be hurting WOT power, so new Chrysler kits were available and I asked the dealer to order one and it was installed. Before the exh manifold was reinstalled, I checked it and it was stiff. I asked "Is that normal?" and the tech got a reamer and clearanced the bushing so it worked freely. I thanked him. It worked as designed, but better than new as it working freely. I checked it a few months later and noticed it was still free. All was good. I was under the hood about 6+ months later and noticed the counterweight was in its prior 1/2 open position and was stiff to move. I got it freed-up again. A few months later, same thing. I realized I had noticed not difference in performance, choke operation, or fuel economy, so I figured "That must be where it wants to be" and left it.
Now, fast forward to the 1980s. By this time, I had become friends with new people who were "into cars" and might be considered "hot rodders". I had read MUCH more and learned MUCH more about cars and such. The prevailing orientation was to block the heat riser passage to "make more horsepower". I could understand why, but also knew about where the automatic choke thermostats were on many engines, back then.
One of my closer friends, back then, had a '79 Corvette that he was doing some things to, but also it was his main car, so it had to be used daily. He had the intake off and also installed an intake gasket with the blocked heat riser passage. Later, I asked him if it made any difference in cold-start drivability. He thought and replied that he hadn't noticed anything. Another data point. I had come to trust his judgment.
When I bought my '77 Camaro, I was pleased to see that they were running the heat riser valve with a vacuum actuator, rather than "a spring". I worked around the larger bracket during spark plug change times. Then one day, I heard a loud clanging sound when I started the motor. Turns out the actuator rod had fallen off of the now-elliptical ball stud, so the valve was reacting to pressure pulses in the rh exh manifold. It was put back on, but it was also obvious that "something else" needed to be done. I ordered-in the heat riser for a '69 Chevy pickup (we had one of those, too) with a 350 4bbl V-8. A nice self-contained unit of the correct diameter that would slip in where the '77 item had been. No actuator needed, as it was counterweight-against-spring in operation. Except it got "modified" as the next engine would have the '86 L98 Corvette aluminum heads on it, with no heat crossover passages in them. Still needing the build thickness of the '69 valve so the y-pipe would bolt up as normal.
I had liked the cam that I had put into the 305 and it had a Holley "28-Z" 4bbl single-plane intake, with a 9895 Holley spreadbore OEM-spec replacement carb. I had fine-tuned that carb so the choke would come off within the first two blocks of driving on a cold start, running reliably too. Spark plugs initially were NGK V-Power plugs, which helped in my tuning activities.
So, at 525K, the 355 went in. I immediately discovered that I needed to tweak the elec choke and fast idle speed setting a bit. With no exhaust heat, the engine was a bit more cold-natured, compared to what it had been with the iron cyl heads, open heat crossover, and aluminum intake. BUT the heater got hotter quicker, so that was a plus! After about 2-3 miles of driving in 40*F weather, or a bit cooler, enough heat had migrated from the cyl heads into the intake manifold so it ran normally after that -- KEY observation. When I later added NGK Iridiums into the mix, it seemed to help the cold driveability some, as they would tolerate a leaner mixture than normal plugs would, although the V-Powers were the next-best thing to them, in that respect.
NOW . . . how one drives after that first cold start is KEY to whether or not the heat crossover not being their works for them. My friend with the Corvette only had to back out of his driveway, drive about 40' to the corner, stop, turn and drive nearly a mile to the main steet to go to work. Hence, little time spent in true warm-up mode. He said "no real difference" to the heat riser passage being blocked.
I would back out of my driveway, drive about 300', slow for a turn. another 300' and a stop sign. Then another 7 blocks to a stop sign and cross-traffic I had to cross and turn left. By that time, my Camaro was fully at hot base idle and accelerated normally. Which is exactly what I wanted it to do. AND, I had switched to an open-element air cleaner, which meant only ambient underhood air went into it.
NOW, as to our Chrysler 383s, even back in the 1960s times, they DID have hot restart issues! Even back when only a smidge of ethanol might have been used as an octane enhancer only. I read everything I could on fuel bowl percolation, back then. Not much I could do with the stock carb in that respect. The float level was to spec, meticulously so. When I got my '70 DH43N car in 1975, with a stock AVS, it was typical/normal in the hot restart situation, too. Plus the heat riser issues. The automatic choke was set as lean as possible, consistent with good cold start driveability, with normal spark plugs and such, back then. Then came the '67 Newport 383 4bbl in 1981. Normal heat riser issues, same hot restart issues with the stock AFB. The current E10 fuels are NOT the cause of the hot restart issues, just makes it a bit worse, by observation, due to the fuel's higher volatility (which is also better for fuel atomization).
NOW, as to "does it work" questions. This is variable as to the sensitivities of how well the engine runs when first started and for the first few miles of driving (in variable driving speed patterns). Even if it might die a few times, some might dismiss that as a price to pay for allegedly better WOT power, BTAIM. We all live in different climate areas of the country. What can work well in Southern California or Houston, might not work well in Indy or Columbus, OH, and certainly not in Canada (except in the summer months). Lots of variability in where this forum's members live.
When I put the Torker II intake on my '67 Newport, it seemed to run better, all the way around. I initially used the recommended/calibrated 9801 TQ carb, but had a few used OEM-spec Holleys in the mix, too. Might have been better on the hot restart issue, but I just did what it wanted to get it to start quicky, as to throttle position, hot or cold. I don't recall if I put the "insulator" back under the intake or not, but probably not. ANOTHER factor!
So, my recommendation would be to leave the heat crossover passge OPEN and working, but block the heat riser open or remove it completely. There should be enough pressure pulses to pull heat into the passage, from both directions, to heat the intake so the divorced automatic choke can work decently well. Remove the insulator bag from under the intake manifold, which opoens up air flow to the bottom of the intake for cooling. Just like the "Air Gap" intakes, Buick Nailheads, etc. That, in itself, can help lessen the hot restart issues, I suspect, as convection cooling can take place, better, I suspect. An aluminum intake can also aid in heat dissipation, too.
Use the thick, OEM carb base gasket, for its insulation properties. The aluminum baffle insulator gaskets that GM used and Holley sold, did not seem to help enough to make them worthwhile, in the 1970s, by observation. Their extra width and length might have shielded the carb from rising heat, but it also could block convection cooling, too. But they looked like they would work!
In using the thicker gaskets where they were not originally used, two things. The choke thermostat springs can get tighter with age, so raising the carb 1/4" can help to counteract that. In the end, though, NO big deal to lengthen the rod in the slight bends before it attaches to the choke linkage. Normal pliers work well for this. Having the choke plate just close at about 68*F. Then using the vac pull-off linkage to open the choke a bit more, by widening the bend in that linkage. A medium-wide flat blade screwdriver works well for this. If too much, easy to close it up a bit with a pair of pliers. Tweaking as needed for YOUR conditions, using the factory specs as a baseline from which to work.
Usually, as the electric choke carbs are received, their choke thermostats are set "too tight", to me, so do NOT hesitate to set them from 1-2 notches leaner than received. Holley used to sell a "Thermister" to vary the amount of current going through the elec choke coil, as to engine temp. I tried one and saw now real changes, but it might have worked differently in a colder climate than in N Tx.
The OTHER component in this equation is the ignition system. In theory, even a very rich mixture should be easier to fire-off after the richer parts get circulated through the motor, during starting. Which means the hottest spark at the correct time, to me. Making sure the coil is delivering the spark it needs to is important, while starting. Having spark plugs which expose more of the spark kernel to the mixture just helps things along, with better "POWS". The NGK V-Power plugs do this, although normal plugs can be modified a bit to get basically the same result. With the fine-wire Iridiums being the best in this respect, as produced. The ACDelco Rapidfire plugs came with "every trick in the book" (later 1990 era), as produced, except for the fine-wire electrodes of the NGK Iridiums. Somewhat easy to duplicate what ACDelco did, if you want to invest the time.
As to the valley pan intake gaskets, the reason for the paper gaskets in the kits, as ithey nitially came only with the 1969 440+6 aluminum intake applications . . . they are to be used when aluminum heads and/or aluminum intakes are used. Keeps the harder metal from "marking" the softer aluminum mounting areas of those items. Which can also compromise the seal, over time.
Thanks for your time. Sorry for the longer length, covering my experiences and observations from 1967 forward. YOUR experiences might vary, which I respect. Whatever works!
Enjoy!
CBODY67
