If his non turbo trans is a 3 speed auto TH-200 (has a square pan with a corner cut off, held on by 11 bolts and has the word "metric" stamped into the pan), I would not use it with a turbo 3.8 because they (TH-200) are one of the weakest trannies used....and a turbo 3.8 would certainly blow it apart the first time he tried to get on it.
If your friend has access to the car the turbo 3.8 came out of, his best bet would be to grab the original 200-4R trans, 8.5 rear, the gas tank, exhaust, intercooler, the wiring harness.....yeah there's a lot to converting a non turbo car to a turbo car.