if you want to get motoring as fast as possible just bang the engine in with the existing drivetrain.
It will mate up with whatever box you have there quite happily.
Need to use a lower offside engine mount, use the 5 mount.
Then its the fueling and exhaust to worry about.
The wiring isnt hard either.
A grand pah, that could get you 2 19 16Vs and full tanks for that if you shop around, or 1 pug 405 MI16 and a 205/309 to stick the engine into.
Also the GTT lump is not unreliable. What makes it un-reliable is idiots winding up the boost making the air as dense as Stephen Hawking (not very) and as hot as the arse of the sun causing nasty things to happen. And the fact the coolants rustier than the titanic and 80% of the rad is blocked.
The GTT engine is a good engine despite is shortcomings (non crossflow for examplke), it will last if treated properly and will make big power, all day everyday if it has to.