Without getting too detailed, sounds like some marginal machine work to me. Which number cylinder? How hot did the block get? Was the overheating because of a coolant issue or from the piston itself? Can you post pics of the piston, pin, wall?

If I were you, I would pull the block and find another to rebuild.

Once you grenade a block, there is no going back. If you have a very nice numbers matching car, the difference between having a usable correct block and not can be a difference of $3000-5000 if you choose to sell your car.