Got engine apart

If it's still std bore, then adding new pistons will still leave them lose in the bores. If your choice is KB hypers, then this simply wont work well. I will also say technology has come far in 15 years. I would do a rebuild on the lower end, meaning check the crank and rods, chances are they are fine. But plan to bore and hone the block, and plan to re-balance the assembly.