If they are all stuck, it can be a bitch. Any rod caps that you can get off, you can pound the pistons out from the bottom. As long as they are hooked to the crank, they all have to free up at the same time. If some come out, put the heads back on and shoot a pressure washer down the plug holes. Push hard and the water pressure will move the piston if it can move at all with the crank not free.