Depends on year of harness. Early harness is two piece. Upper harness is for injectors and lower for spark. You can leave in your old distributor and use injectors or you can install the whole system. There is a wire that needs to be connected to switched power by the coil for the injector ecu to work.
You will need to integrate the wires for switched power, constant power, water temp, oil pressure, fuel pump, alternator, tach and starter.