listen to what this man has to say. A GTR or GTS4 AWD chassis is completely different to a RWD chassis. Which means the crossmember is differnt and the rails are different. This means you'll have to change crossmembers, source front hubs etc and a whole lot of rubbish.
We get offered R32 and R33 GTSt wrecks all the time from guys who stack their cars drifting and accidents... its really not that hard to pick up a repairable shell these days.
Keep it simple, and save yourself the hassles. Sure the GTR look is tough, but is it worth the hassle, when you can get fibreglass guards that achieve the same look on a GTSt for much less effort?