A dog is a dog, just cause its got a GTR badge on it dont think it cant be a lemon.
Engine/Turbo all you can do is check for excesive smoke from exhaust, check to see if timeing belt has been done, and if so the water/oil pump.
Driveline/Clutch check to see if clutch is holding up or slipping, change gears quite quick under load to see if syncros are ok.
Check brake disks for cracks.
One of my AFM's went in the first week.
Try and avoid 1989 GTR's if you can, most of the good ones are long gone.
A modified R32 costs about the same as a clean stock R33 , decide wehter you want the newer cleaner GTR or the modified faster one.
You can often get a FEEL for a cars state of health and condition by driveing it and giving it the once over, other than buying it from a dealer, thats about as good as it gets. GTR's with full service histories are rarer than a Honda Civic without a Mugen Power sticker...