I'm installing a Mallory HEI distributor in my stude. Engine is a chevy 350. Installation instructions say to connect the chevy wire harness as it had been previously. But i was running a dual point with external coil before.... The HEI has a terminal for the + from the battery, - coil, and a ground. My question is, is it necessary to connect anything to the - terminal and ground terminal? I assume the + connection is the hot from the key switch.