A cub engine I bought a few years ago, seized up,in storage. I put Kroil in the cylinders, but was not able to free it, by cranking it. Without a bolster, to support the crank, you can't apply much torque. I devised a tool, attached at the flywheel end,of the crankshaft, from some scrap steel. One hole slips onto the alignment pin, and two bolts secure it, to the crankshaft.
One tug, on the secure handle, freed the engine. The engine was securely mounted on an engine stand, during this procedure.
A flywheel was used as a template,to align the holes. I used a mall scrap of approximately 3x4x1/4 inch stock welded to a scrap of "T" shaped stock,about 2 feet long, but it could be made of one piece of flat stock, if you don't have a welder. Ed