What is minimum electrical required to start my car?

Get a magneto, you could crank start that motor. Kettering ignition (points) take nothing but battery voltage. you can run it off a 12v lantern battery once its started without an alternator. Ever throw a alternator belt, car keeps going on battery power. Coil/points take about 4-6A to run so theoretically with a 50A/hr battery a car could run 70 hours with no external charge. Starting is a big chore, could draw 100A easily: probably more with the old Mopar starter.