Electronic ignition upgrade.

And another thing about the factory ignition; IF it does breakdown, 500 miles from home, parts are only as far away as the nearest period mopar. If you go to a Mopar car-show, chances are that every second car in the show has a spare of whatever you didn't bring.
The only part I carry a spare of is the Pick-up, and NOT because they fail; rather because, they have the potential to fail, first.
I've been driving Muscle-car era Mopars, almost continuously since 1970, and in all those over fifty years, the only failures I have had are; one pick-up, one Ecu, and two resistors.
In a pinch;
> you can run both the ECU and the coil off the same resistor, and
> in a bigger pinch, you can run the coil straight off the battery
> and, one time I had an aftermatket EVR fail, full-fielding the alternator, which then pumped out over 20volts, meaning that after the ballast, the ECU was probably running at least 50% of that and the coil more like 70%. Moparchit is tough. I replaced that EVR, with one from my bin of well-used parts.

OP, in my experience, any period Mopar will run off any period ECU, to at least 4000/5000 rpm; number of cylinders means nothing. All the ECU does is amplify and translate the tiny voltage coming out of the pick-up, into something the coil understands.