I know a guy who is well known for his custom harnesses. He got well known for putting LS1 motors into the mid-90's RX-7s. I can ask him about it. I don't know what he charges for making one. But he made it plug and play. Everything worked like factory. A/C compressor kicking off like it should under WOT. Gauges all worked. Really nice stuff. He has done a ton of work for folks who have had their stuff butchered and he has come in and saved the day countless times.
If you can get me that info, that would be great. I would really appreciate it!