My recently acquired Challenger had been running on a Mopar Chrome box P4120534, .25 Ohm ballast and Mopar Repro oil filled ignition coil that is mounted horizontally on a six pack intake.

I found the coil was failing under load by swapping with a red MSD Blaster coil I had from another car.

Read an epoxy filled coil is best due to horizontal mounting so purchased the MSD HVC coil. Installed and life was great for about a day till it mysteriously stalled at a light with a crank, no start condition. Let it cool down and it would start up briefly and stall again.

Chased my tail since I didn't feel the new coil would be bad. I swapped the .25 Ohm ballast for the recommended .8 ohm. No dice.
Swapped the Chrome box with a known good Echlin, no dice, still stalled.
Measured pick up coil resistance, was good at 295 ohms and register .5vac while cranking. To be safe, replaced pick up coil with new one and same results, still stalled.

Swapped the new coil and put my MSD red coil back in, all good and no stalling.

Received a new replacement MSD black 8222 coil and run it with the .8 ohm ballast. Drove it an hour and no stalling so I'm guessing fixed.

I called MSD Tech support to get their final word on the correct setup with their coil and what ballast. The person I spoke to was not even familiar with a Chrysler electronic ignition which killed all my confidence in them. He initially said it shouldn't need a ballast since the ECU switches the coil but then changed his reply after I told him the stock set-up uses a 1.2 ohm ballast and a 1.5 ohm coil.

My concern is...
- what have you folks successfully run with a Mopar Electronic ignition with MSD coil?
- Can I potentially have a Chrome box overdriving the coil? I have left the Echlin stock unit in for now but concerned since I've read due to the low coil/ballast combo the ECU can't handle the extra current.

Appreciate any light to be shed on this.
Trying to avoid installing a CD ignition like MSD 6AL since I want to keep it all Mopar if possible.
Thanks in advance