You bolt the flywheel on and spin it with that. Or if no flywheel you put 2 or 3 bolts in the back of the crank, stick a crowbar in there and rotate.
And you should make sure you get the block checked out for any issues plus make sure the bores are good. If not you can get them honed .010 over or bored .020 over.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.