Fox Body Mustang, blown engine. <---Rookie Question?
Your engine likely needs a rebuild with a .030 overbore, and new pistons which use a 5/64th piston ring instead of those damned metric low tension rings. If you elect to buy a long-block, make sure it has forged or hypereutectic pistons and not cast pistons. You could get a short block and throw some aftermarket aluminum heads on the short block....