Your best bet it to start with a wrecked GT. There are lot of little odds and ends you'll want. Motor, harness, fuel system, dash harness, cluster, ECU, front springs (they are a different rate than the V6 stock front springs) and a lot of little things.
Personally, I'd take the engine on the K member, trans and rear end all at once, then swap all the harnesses etc... It's too much work for the little power gain IMO.