The red exciter wire runs from the back of the alternator to the battery light in the cluster. The oil pressure light sender is the sensor you refer to and has a black wire attached to it. Both wires go yo the cluster through the large grey connector at the center of the firewall. Run new wires from the alternator and oil pressure sender to the grey connector and splice them onto the appropriate wire.

Wires can be run on the passenger fender well to the firewall to keep things need and organized.
Dan