I found a Specialized Rock Hopper, Large frame, 1992 bike that has been serviced recently and is in good shape with new tires and stuff. Well taken care of. I'm 6'2". Will this bike fit me ok? I don't want to drop $100 on a bike that will not anywhere near fit.
You're in the right ballpark, but there's no way to tell for sure without a test ride, or some more specific measurements. I'm 6'2'' with 32'' inseam and for most mtn bike frames, I'm in between a L and an XL, depending on the brand of frame, and how they take the measurements.
'92 is gonna have the old geometry with a high and short top tube and probably like a 135mm stem or something kind of rediculous... anyways it should fit you if you run a little extra seatpost, but the stem thats on it now is probably about as long as you'll find (unless its been changed)