Ignition issues...

A 4 pin should run on a 5 pin harness "the deal is" that with the 4 pin resistor, the "2nd half" of the resistor fed power (to the older) 5 pin ECU. The 4 pin does not need that

You MAY have a problem with ignition switch/ wiring/ bulkhead connector

Here is how a Mopar ignition switch works:

The "run" power which comes out in the engine bay feeds power (depending on year/ model) to the ignition system, alternator field, voltage regulator, sometimes some smog doo dads. THAT POWER IS ONLY HOT in "run." It GOES COLD IN "cranking." This power comes from the IGN1 terminal of the key/ ignition switch

So this means there must be a SECOND source of power for cranking and that comes from the IGN2 terminal of the switch. This is the "coil bypass" circuit and is the ONLY source of power for the ignition system during cranking

So clip your meter to coil + and see if you have power. If not you'll have to find out why. Next I'd access the ignition switch connector and see if you have it there

Go to MyMopar for free service manual downloads and other wiring diagrams. Some of them there, came from the guys here

NOTE: The ignition switch diagram in the 73 shop manual is drawn somewhat ambiguous. They imply that the yellow "start" terminal of the switch (which fires the start relay) and the brown bypass circuit are connected. THEY ARE NOT. They come off separate dedicated switch contacts.

There are many many posts on this issue on here, do a search