What coil are you running?

I would not use an e-core coil with a ballast. That is unusual and throws another unknown into the equation. You want to get to a known baseline. I am pretty sure the factory coils varied between points and electronic, since I have one stamped "for use with electronic ignition only" (at least I recall the "only"). So don't use a points coil to avoid another unknown. Among Mopar ECU's, there are a bunch of bad, or at least unusual, ones out there. A recent post showed a dissected failed one with a fake TO3 transistor on top and a small internal transistor that didn't touch the case well, so more unknowns. You will probably never get firm conclusions without a big budget and lots of experiments. Better to just find something that works. I doubt HEI modules have a generic problem, or Chevy's would always get stomped.