Try some Kroil:
www.kanolabs.com Best penetrating oil I've ever used! I've unstuck a bunch of frozen engines with this stuff, and it's made right here in Nashville. Put 3 or 4 ounces in each spark plug hole, wait a few days, and drain it out of the oil pan. Repeat a couple of times, and use a pry bar on the flywheel to roll the engine over. It's supposed to creep through gaps one millionth of an inch in size!
Jerry
