The biggest issue with a motor that has been sitting for a long time will be the rings. They can stick to the cylinder walls, locking the rotating assembly in place. There are a few schools of thought on how to unstick them. You can pull all the plugs, squirt some penetrating fluid in there, and let it sit for a day or two, then slowly try and rotate the motor by hand. Some guys just go for it and hope for the best. We are going to take the safe route and tear the motor down to inspect the cylinders before trying to rotate the crank.