The 93 is a great year for the 3000GT VR-4. It has the upgraded engine internals and drive train of the later years, and better gearing for the 1/4 mile. As far as mods, anything that will fit a 91 will fit a 99, except for body panels(front end changed in 94 and again in 99).
When ya look at it make sure you dont get over excited and buy it with checking it over. Turbo's normally go around 100k miles, so make sure you figure that in to expencenses if its close to that. As about the 60K service, it should have been performed around 60K miles(reciepts??). And make sure the transmision shifts smooth, if a quick shift results in a grinding, weather heard or only felt in the stick, it means the synco is begining to go on that gear. Not a compleate disaster, but it should be fixed and may bring down the price. For reference a tranny rebuild costs around 2000.
Im sure yogs will pick up the stuff ive missed. Also check out
www.3si.com, lots of info on there.