If you still have a ballast in place, and the mopar ecu box is clearly wired to the distributor...you don't have a "Chrysler version HeI distributor in place" I don't know what you mean by that, but Mopars don't have HEI from the factory.
easiest thing to do in my opinion, is to install one of these inexpensive REAL HEI units...that just require a simple switched 12V to run, and they have a tach lead.
Then your engine would run independent of all the hacked up wiring in the car, and you can start removing the previous mechanics hack jobs.
you said you have a 440...so this would be your easy fix, for the novice mechanic.
TSP-JM6714BL Mopar BB Ready to Run Electronic Distributor. Blue Cap
View attachment 1715039536
you don't mention where your timing is at, and for all we know the carb is worn out, but i'd start here....get it timed mechanically. not even mess with the vac advance, and then start diagnosing carb tuning, and go from there.