Msd Power Source

I can speak for the '65, but don't have a wiring diagram for the '68. The ignition switch has a Red-Green wire coming off it that is 12-Vdc. It goes into a pink resistance wire to drop the voltage down, then goes into the firewall connector to be routed to the coil. You would need to remove the resistance wire section out of your circuit to give you 12-Vdc to the coil in the run position. It already has 12-Vdc to the coil in start via a Brown wire that taps into the Red-Green wire ignition circuit to the coil on the engine compartment side.