Ignition problem

I think you are on to something there, makes sense to me, thanks

If you have a multimeter, you can check the connections through to the ballast resistor junction of the ignition start.
With the battery disconnected, use ohms or continiuity.
With the battery connected, use Volts DC.

I think in this case I'd prefer to measure volts.
Clip the hot lead to the junction on the ballast or coil. Doesn't matter in this case because start bypass the ballast resistor.

Here's diagram showing the connections on a points equiped '72. We'll get to ECU version next.

1708883505707.png
With the key on start, battery power should be available at the J3 to J2B junction. A volt reading there should jump to battery voltage and the ammeter should swing slightly toward discharge. When the starter engages, battery voltage will drop. It should be no lower than 9.5 Volts. if its lower than that, then measure the voltage at the battery during start to see if there is resistance in the circuit feeding wire J3.