Back then, Chrysler's emission reduction package (which had a definite option code) was more "engine modification" rather than add-on parts, as Ford and GM had to do. The Chrysler option code, for vehicles sold new in CA, had a "lean-limit" carb, a distributor with a specific advance curve, and possibly the open-air crankcase breather cap replaced with a closed one whose rubber hose went to an air cleaner snorkel. From what I've read, the Chrysler combustion chamber shape allowed them to do this, rather than need the add-on air pumps and such that Ford and GM used . . . which the accountants at GM crazy.
The Cleaner Air Package (CAP) cars usually had a higher idle speed to better hit the stated idle fuel mixture specs. Some of the 6-pack motors had an idle speed of about 900rpm?? The distributor advance curve was "lazy" up until about 2000rpm, which aided lower emissions. The base timing was usually a few degrees closer to TDC than non-CAP cars. There were a few hidden things in the carbs, too. For a better explanation, there's a Chrysler MasterTech training film on the basic system and how it evolved in later years. You can find these online through a few websites. Possibly
www.mymopar.com and the
www.imperialclub.com website, plus a few others.
NOW, the worst case scenario is for you to have to pay for an emission test by an approved test station in CA. You can play with the carb idle mixture to hit the stated fuel/air ratio, which is what the whole deal is built around.
At this stage of the game, ANY replacement carbs and distributors will be "will fit" rather than "OEM-spec" for particular applications. So chasing the correct number distributor and/or carb numbers might not yield the desired results.
So, put some B-12 carb cleaner in the tank and take it for a long drive at highway speeds. Pus some new spark plugs of the correct heat range for the CAP cars in the engine. Spray down the carb's throttle body good, put a new pcv valve in, new air cleaner filter element, AND change the motor oil and filter. Then take it to a certified (I believe that CA requires this?) tech that is approved for emissions repairs/testing. See how it tests out with the stock specs and then see if the CAP emissions specs can be attained. ONCE it does, I suspect they'll print a document of the test results with "PASS" on it, which should be what it takes to get things taken care of, I suspect.
KEY thing is to have the car fully at operating temperature when it goes into the test cycle. The oil change is important as any "blowby" HC or CO past the rings goes into the crankcase oil and can be re-added to the air/fuel mixture in the cylinders. So minimizing that situation can be important!
ANOTHER side of things is that CA has seemingly required a "retro-fit kit" for older vehicles (starting with 1955 models?) that will make their California Air Resources Board (CARB) compliant. Worst case scenario, you might need one of those.
As far as getting anything from FCA, as requested, probably not going to happen. Seems like the option code was "N95" for the CAP option? Which would be on the data plate under the hood, IF it was on the car.
On our then-newer '66 Newport 383 2bbl, when they did a tune-up at the local Chrysler dealer, they'd always hook the car up to a air/fuel ratio tester to see that the carb was working correctly. Once, I asked if it was possible to get the idle mixture adjusted to 14.0-14.2, on a non-CAP car. It happened, but the manifold vacuum went a little lower and the engine wasn't quite as smooth, BUT it was possible.
In later years, possibly the best idle mixture setting procedure is the "lean-best idle" method. With a dwell tack hooked up, the base timing set, then set the hot base idle speed to spec. From there, turn each idle mixture screw CCW to richen the mixture and possibly increase the idle speed. When that is maxed-out, reset the idle speed down if needed. Then turn each idle mixture screw CW to result in a 20rpm drop in idle speed. Then put it back where it was. Do the other one the same way. It might take a little "back and forth" before you're done, but that's fine.
Some like to use a vacuum gauge instead, going for "max vac", but that might put things more at the rich side of the scale rather than the leanest it can be with the best idle quality at the same time.
A friend in our Mopar club had a '70 Road Runner 440+6 car that he drove and raced. All bone stock specs, just well-finessed. It would pass emissions for 1975 models without any catalytic converters when set to stock specs. That was in the early 1980s. With the greater oxygenates in the current fuels, might even do better?
Your car is not the first car with Federal specs that's been registered in CA. Nor will it be the last. Getting the letter from FCA is the easiest item to do, but getting the car to meet the CA specs on a test would be more difficult, in comparison. And that's probably where you end up, getting the test at an approved testing station (possibly operated by CHP?). Just a few extra hoops to jump through . . .
Keep us posted.
CBODY67