I'm sure you could find thousands of words on this site about reviving long-dormant engines. I just want to say that you may want to avoid even hand-cranking this engine until you pull the plugs, squirt a small quantity of good engine oil into the cylinders,let it sit for a day or two, then WITH THE PLUGS STILL OUT hand-crank it. I'm just concerned that a ring or two may have bonded to the cylinder walls. Hand cranking a dry engine under those circumstances might break those rings.
In this particular case, I may be advising you to close the barn door after the horse ran out.