Turbo motors

Wiz, when you say "a full wiring loom to the ECU", do you mean from the engine to the ECU, or the body loom to the ECU? Also, there isn't such a thing as a 4SGTE. There's just a Rev 4 3SGTE.
 
Anyway, RPM garage has an original 1997 JDM loom for sale – pretty crazy prices though. I've bought a few things off RPM Garage, and never paid the orginal listed price, so I'd make an offer knocking quite a bit of what's they're asking and there's a good chance they'd accept it.
 
Each section is listed seperately and they seem to have two sets for sale:
The engine loom: https://rpmgarage.com/index.php?id_product=1408&controller=product&id_lang=1&search_query=mr2&results=142
https://rpmgarage.com/index.php?id_product=1274&controller=product&id_lang=1&search_query=mr2&results=142
 
The body loom:  https://rpmgarage.com/index.php?id_product=992&controller=product&id_lang=1&search_query=MR2+turbo&results=115
https://rpmgarage.com/ind...+turbo&results=115
 
Another option is buying one off yahoo auctions in Japan, via Importmonster. That would work out MUCH cheaper once you found a listing for the right bit of the loom. Here's one of an unknow year (for a 3SGTE) with every single bit of the car's wiring, currently going for $69. (Postage and importmonster's commision would be on top of the price, but you can calculate an estimate for the total cost on the importmonster site.)
 
http://www.importmonster.com.au/view?url=http://page2.auctions.yahoo.co.jp/jp/auction/b248408067&thumb=https://auctions.c.yimg.jp/images.auctions.yahoo.co.jp/image/dr516/auc0302/users/6/6/3/5/khtauto-thumb-148791106493284226531.jpg&title=A197%20SW20%203SGTE%20MR2%20F%20BOX%2011%20z
 
You friend could buy that, then have an auto electrician re-pin anything tha's not in the right place and still come out way ahead.