id rather build an awesome GTSt with a 26, that wasn't trying to be a GTR.. for the expense of making a GTR faker you could've just used a combo of aftermarket parts (guages, seats, brakes, etc) to make a way better car anyway...
what are you gonna do with this GTR with half a driveline when you're bored of it? doesn't really sound cheap/easy to reverse the conversion... and if you wanna sell it, who's gonna buy it? etc