I have started many of them on 12 volts. Disconnect the wire going to the rest of the truck electrical system so you will not damage any gauges or other equipment. I always put an ignition resister in the jumper going to the power side of the coil. Get one for a late 50's chevy. They are not expensive. Without it you will burn the points.
George

They say money can't buy happiness. It can buy old Chevy trucks though. Same thing.
1972 Chevy c10 Cheyenne Super
In the Gallery Forum