Try some heat to the outside of the cylinder.I got a 930 Jred that was seized solid,when i picked it i turned it over and water ran out the plug hole.I took it as a challenge to save at least the cylinder,i did.The piston is still usable as well.
I used "Honey Goo" and a Map gas torch.I would heat up the cylinder around where the rings were till i couldn't hold my hand on it and pry up on the cylinder.When i heard the first squeek i knew i could win. Never even broke a fin.Not much else that is usable,maybe the case halves.