If you're doing a full wiring harness install, seems like it would be convenient to test the non-motor-related circuits while the engine is out? Make sure to protect any dangling powered engine wiring (coil, ballast resistor, etc) from shorting. Then, connect the battery and verify headlights, tail lights, brake lights, interior lights, radio, turn signals. Since this reply is almost 2 weeks late, you might have the engine back anyway?
