Nice car! I wish my car had an up-down switch on the dash!

I would try getting the stock carb working before going aftermarket. That carb was calibrated to your engine by Chrysler engineers who spent hundreds of hours getting it right. Since you have a stock engine, if you can reclaim the original calibration, you'll be head and shoulders above taking a universal carb out of a box, bolting it on, and expecting it to be matched to your engine.

If you'd rather check what you've got before spending the money, you can have someone check the air-fuel ratio with a wideband meter. It's possible to check it at the tailpipe (so you don't have to install a bung) but it's not quite as accurate. Still better than nothing, though.

Since you seem unsure of your ability, carb wise, I'd recommend talking to good carb shops (some of whom are Moparts members) about refurbishing your carb and (here's the important part) maintaining the as-delivered calibration.

Otherwise, be sure your vacuum advance is working (as others have said) and if it's tunable, be sure it's coming in soon. You should have 38 degrees total advance by 2500 RPM or so with the vacuum advance disconnected.

Did I mention that I REALLY like your car?

Jim

ETA: I checked my original carb, and mine is a 4326S - I would guess that I'm one number off from yours due to the fact that mine is a 4-speed. Mine has 350 and 498 jets. The metering rods don't have numbers that my 49-year-old eyes can read, but I'll be happy to check them with a micrometer and let you know the measurements. The metering rod springs - I have no idea how to identify the ones in my carb.

If you're concerned that someone has changed parts in your carb, using the same calibraration as mine would get you darn close.

Shout back if I can give you any more info.