There are ECU pinout patterns available on some websites. You could study that and try to work it out. This is one of those things that seems really hard, until you give it a go and muddle through. If you are just chucking a RWD engine loom and standard ecu in the car then you should be able to more or less plug and play with it. There will be a few power feeds and grounds to connect, and posssibly some routing issues depending on where you can stuff the ecu. You will need to wire up a short engine harness, like a 4ac rwd one from ae86/71, to trigger the starter, connect reverse lights and oil pressure warning light. Hope this helps.