i would never put in a used piston.........
here's a question for you....
you put in a used piston/rings, that are worn, this causes excessive piston to wall clearance, and the skirt breaks off of the piston, and the crank shoves it through the cases, and the debris goes through the bearings in the crank....
something similar just happened to a member on here (not exactly the same situation but similar)
so now that you need another top end, piston, cases, and a crank, plus tools or pay someone to rebuild it, how much cheaper was it again?