It sounds like one of two things, loose or dirty connection on the ballast resistor or a wiring problem from the ignition switch to the ballast resistor.
Someone put that motor and ignition in that car, check all the connection closely first and then use a volt meter to check the voltage (check the voltage at the battery first, if it is around 12.6 volts) to both ends of the ballast resistor, you should have almost the same voltage,12.4 to 12.6 V, at the ballast on one end and around 6.0 to 8.5 volts to the other end with the key on and the engine not running Next thing is to put the shifter in some gear position other than neutral or park and have a helper turn the ignition switch to the start position while you check the end of the ballast resistor that had the lower voltage with the key on, it should increase to battery voltage or a tiny bit less in the start position to that end of the ballast resistor to make the coil fire when in the start position
Mopar electrical engineers made it harder on us to trouble shoot problems in their design of theses cars
Let us know what you find and have to do to fix it, that will help others on here later