Ignition system, battery to starter/solenoid

You're welcome. If it helps any, if you happen to be familiar with other older cars like GM and Ford, they too had a bypass circuit, except Mopar did this at the key switch, and Ford/ GM did so at the starter solenoid. "A look" at older GM solenoids, or Ford fender mount solenoid/ relays shows they have a small "S" terminal (start) and "I" terminal--which is the bypass. In these cases, the solenoid has a small contact inside which energizes that "I" terminal during "start" and sends that power to the + side of the coil. Works same way as Mopar except for components used

I don't know how such as Holden did this back in the day