Billm, Kroil, ATF and diesel, penetrating oil, molasses, coca cola, or some mixture there about put into the cylinders will help dissolve rust on the rings.
Remove the valve cover and loosen all the valve settings so you don't bend pushrods when it does turn over.
Remove the flywheel cover and pry on the flywheel with a crow bar gently in each direction. It will eventually break loose.
