I would post your issues in the appropriate engine forum on this site. The mfg , in this case ,really has nothing to do with your driveline. I would imagine the only wires that come off the engine and go somewhere besides back to the engine are the ignition wires. And that is probably a total of two wires . A engine of that vintage is going to be as basic as it gets. Is it a I/O ? If so you could have a bad neutral.safery switch which kills the juice. If you still have points ,they could be shot. Even if you has a wiring diagram it wouldn't help with your no spark on a 72 block.