You would want to run a P72 if you want the knock sensor and secondary butterflies to function. Make sure it is an OBD1 to match the engine to make it the easiest.

There is no logical reason why you would want to run an OBD2 ECU. The OBD1 makes the most sense because it is less complicated, can't learn around piggybacks, doesn't require any additional sensors and wiring, and it is what the engine was made for.