Just had a thought,
GTR fenders, whatever bonnet. grill, bar and rims you wanted. Added cost of spraying and fitting = ~$7-8000. Maybe more, I'm no expert on costs.
Sell your GTSt + at least $8000 = GTR. Its win win, plus you get an RB26, 2 turbos, 4WD, 4WS, GTR seats and a GTR badge