Again, we are talking about the ECUs, not the ENGINEs.

The engines are virtually identical. Only difference is the OBD2 has some more emissions stuff and it has a Crank Sensor on the Oil Pump.

OBD1 has the sensor in the distributor.

other than that there is almost no difference.

The ECUs however there is a HUGE difference.

You can buy an OBD2 engine, just make sure you convert it to OBD1 ECU if you are going to tune the car