If the pistons measure up to specification than reuse should not be a problem.

If I were rebuilding it, I would prefer installing new pistons. I would hate to think that I saved a few bucks only to dismantle and reassemble the engine a second time in a short amount of time. I do not care to do a job this large twice on the same vehicle, and on the same visit.

If you are looking to sell the vehicle plus maintain a good margin than your decision might be to reuse the pistons.