Wiring a Generator using an Alternator harness

[HBCSpeedShop]

Hello all! I am restoring a truck for a gentleman. He had purchased a wiring harness years ago at Carlisle. It is new, however it is setup for an alternator conversion. Unfortunately he is pretty strapped for cash and can't afford to go all alternator or to get a generator harness. So to my question, any clues on how I could make the harness I have work with a 12v generator? All the other wiring has been routed as intended, just wanted to see if I could get someone with experience in this area to offer any suggestions before I start 'testing' other ideas.

Thanks! Any replies are appreciated.