Im tring to hook the electrical up in my 58 pick up to a small block chev that I recently installed in the truck ,I left the wiring harness on the engine that came out of a 80 chevelle back as far as the firewall . All the original electrical is still in the truck , I was going to try to hook the origial generator wire up to the alternator to see if i get power to the fuse panel, I have a wire hooked up from the key to start it but I have no power to the cab ,like lights or heater. any suggestions?