At the machine shop/garage that I worked in during high school we used one bolt front and back with a chain attached to the heads. Those same bolts pulled thousands of motors and they weren't grade 8. Just make sure anything that the chain can damage is out of the way(distributor, carb, etc). The shear strength on a bolt that size is way more than the motor weighs. If its coming out at a weird angle set it back down and move the hook on the chain as needed. Good luck!