Sometimes, many can (including ME) read too much into the "HP" designation!
With regards to my '70 Monaco Brougham 383 4bbl (engine code "N"), the sales literature and factory service manual notes "High Performance". It has the upswept exhaust manifolds, factory dual exhaust, and crinkle paint dual snorkel air cleaner. All the cosmetic trappings of a 383 "HP" motor. The upswept manifolds came to be normal issue for 4bbl 383s when the power ratings increased to 330 from 325, in the late 1960s. The factory dual exhaust had the same size pipes as the 440/375 motors, too. By that time, ALL B/RB motors had 1.74" exhaust valves, so prior HP items were quietly introduced into normal production.
NOW, the plot thickens in the case of E-body cars! In them, in 1970, a Code "N" engine was listed as both a 383/330 in non R/T Challengers AND 383/335 in Challenger R/Ts. THEN in one of the Dealer Order Guides, in the engine section, in a Dodge guide . . . there is a note with the 383/335 (in B-bodies) that if a Super Bee is ordered/built with factory a/c, the 383/330 will be substituted. This INCLUDES the Super Bee models, it states.
I believe the factory a/c cars were supposed to be painted "blue/turquoise" and the non-factory a/c cars were painted orange? My neighbor ordered a '68 Satellite with the "383 HP" 383/330 in it for high school graduation. HP exh manifolds. Open element "Road Runner" air cleaner, too. With factory a/c, so the engine was "blue/turquoise". Later, he drag raced the car. It ran very well!
So, looking at cam specs and such, it appears that "WE got played" in many respects! WE normally suspected that any "383 HP" would be the Road Runner non-factory a/c motor, rather than just a normal 383 4bbl 383/325 motor. (with the 256/260 cam in it). FWIW, my '70 Monaco DH43N will run 20-100 in just under 4/10 mile with 3.23 gears and P225/75-15 tires. Open the throttle at 50mph and it eagerly sends the speedo needle toward "triple digits" without thinking. Oh yeah, it has the Carter AVS carb on it, too.
The HD valve springs will NOT make power, just more durability at higher rpms as time progresses. To support WOT power for extended periods of time, as with a law enforcement vehicle chasing somebody. The double-roller timing chain is more durable and lasts longer than a normal chain, too. The windage tray can be a toss-up.
In some years of Plymouth Fury police cars, like 1969(?), the 440/350 was the top engine, not the 440/375. Why was that?
To fully assess the "HP" notation, one has to consider against what it is compared to! With the main issues being "4bbl and dual exhaust", at the very least.
END RESULT . . . use ONLY the VIN code to determine what came in the car, period. Then look at the VIN decoders for a C-body to go from there. THAT might not give you the "bragging rights" you might desire, but it is at least accurate for what the car came with.
Tune and tweak to get the engine running as good as it can and BE HAPPY with the results. It still IS a Chrysler 383 4bbl V-8 (and all that means).
Oh, all 383 4bbl in 1970 had the 10.75" torque converter, rather than the normal "2bb;" 11.75" converter. Which means it takes about 1-2 quarts less atf to fill it on a fluid/filter change. On my '70 DH43N. A bit higher stall speed? Yep.
Enjoy!
CBODY67
