The best rout is using a harness. There are a lot more advantages such as chipped obd1 ecu's and far less codes to worry about. Also there would be alot more work to switch the oil pump and You would have to buy A obd2 oil pump, new oil pan gasget, oil pick up gasget and front main seal. RUN OBD2 HARNESS ON THE MOTOR + CONVESION HARNESS TO OBD 1 ECU.