77 wiring harness into a 78

I am installing a 77 wire harness into a 78. The harnesses are different and am wondering if the ECU from the 78 will work?

The main difference in the harness is that the early 77's had the underhood relays positioned elsewhere, I think under the dash on the drivers side. Will using the 78 ecu work??

Also would a 2+2 harness be any different?

Edited March 25, 201114 yr by az240z