You can't get any pistons out? You should have a least a couple of pistons near TDC at any one time so work on those first. Take the rod caps off and tap out the rod bolts so you don't scratch anything and then pop those pistons from below. Once you get those guys out move on to the next couple of pistons that you can get to. Once you get 3 or 4 easy ones out you might be able to rotate the crank and get the next ones out.
This, and what Andy said earlier.
I've had pistons that I could not remove with a 2 ton hydraulic jack but I could beat out.
If you have not hit it hard enough to bust out the piston top, you have not hit it hard enough. You have to use a sledge hammer, unless you are a really big guy that know how to swing a 3 lb hammer.
