Kevin, an engine that's stuck that tight is going to need to be rebored, guaranteed. Maybe even sleeved on a few holes, depending on the current bore size. Pull the cylinder head and use a big hole saw in a variable speed drill motor or a drill press to cut through the piston crowns just inside the rings- - - -about 3 3/8" or so. That will free things up so you can break the centers out of the pistons with a BFH and a block of hardwood. Then go ahead with the rebuild.
Jerry
