Ditto on the Kroil. Drain the oil out of the pan and reinstall the plug, then pour 2 or 3 ounces of Kroil into each cylinder. After a week or so, you'll be able to drain the Kroil out of the oil pan and pour it through again.

DO NOT try to roll the truck to free the engine again- - - -if you haven't bent some connecting rods already it's likely to happen the next time. It's also possible to break an axle shaft or hand grenade some transmission gears that way. Put the trans in high gear and gently rock the truck back and forth if you choose, but the best approach is to use a pry bar on the flywheel teeth after taking the clutch inspection cover off the bellhousing. If nothing else works, pull the cylinder head, use a piece of hardwood on top of the pistons and pound it with a big hammer to break the rusted rings loose. If it's stuck that bad, you'll probably need to rebore it, or sleeve a couple of cylinders.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!