I don't know about this particular swap but from my experience in doing a diesel to an '83 B23 swap I know I had to swap the cars inside harness from the fusebox out to where the engine harness plugs in. There were enough differences that it was easier than trying to sort out the different individual wires out of the original harness. I'd imagine that you'd have to do this too. BTW, if you end up having to do this then it's an ideal time to pull out the complete heater box unit and replce the heater core, blower motor, resistor, and heater control valve. It's alot easier on the bench than doing this in the car later on. Good Luck!