Minwax water base urethane turns to goo when exposed to nitro fuels
Nelson hobby http://www.nelsonhobby.com/paint/paint.html sells a supposed clear finish that wont yellow and tower carries the chevron polyurethane clears. although I hear the gloss clear does yellow with age. I have used the chevron flat recently and it worked very well with just a hint of yellowing although it really is more of an eggshell sheen than a dead flat
I have been told the urethane floor finishes work well but I could only find them in 1 gallon sizes at about 45 bucks a pop