1964 dodge dart 270 hei conversion

I have a 1964 dodge dart 270 that I'm trying to put an HEI in and I'm having a hard time figuring out what wires carry 12 volts. right now I have a wire just going to the battery to start it. Does anyone know what wire has 12 volts that I can run the wire on my HEI to?

a diagram would be appreciated. (I'm bad at understanding electricals and the person helping me mainly only messes with Chevys)