How stuck the rings will be depends on where you live. SoCal or desert, should be easy, Houston - get a big wrench and pray. Just work on it a little each day for weeks. I have heard of everything from DOT 3 brake fluid to Coke used. I would start with WD-40, then maybe try diesel or kerosine. If those just run out past the rings, try thick motor oil. I was unlucky with a Mopar 273 engine that sat outside for years with rain in the valley. After removing the heads and beating the pistons from both sides, with a wood block on top (after soaking for weeks w/ various oils and DOT 3), I got all out but damaged several, and those were rare HiPo pistons. The bores were so pitted it requires an over-bore anyway.
Before turning the engine over by hand, pump oil thru the oil galleys to fill the bearings. I rigged up a garden sprayer with hand pump, with a hose going to the oil pressure switch port, in several engines. I like to do that first if the engines have been unused for several years. I would drain the gas and try to get as much out of the carb as you can, and fill with new gas thru first. The tranny oil should be fine and any condensed water should boil off with first driving, but maybe smart to pull the pan, especially if you live where condensation is a problem.