1977 351W should have a manual fuel pump mounted on the side of the engine, not an electric one. I had a 1986 351W HO and it was still manual fuel pump, not electric. If yours is electric, you have an aftermarket fuel pump. Best guess on how to wire when started is to find a circuit in the fuse box that has power when running and jump that. Another option is to put it on a switch much like some offroad lights, etc. You'd basically have a kill switch that only you would know about. Since the wire was busted up, surely it could be traced to its origin when replacing it?