Crash

The Jeep motor is too tall to fit under the hood.
Your slant is at an angle, the jeep motor sits upright.

Fix the motor you have in it now.
Drain the coolant take a grinder and cut a "V" in the crack.
Dry all traces of coolant out, clean real good with brake cleaner.
JB weld it, let it sit for a couple of days to dry real good before adding coolant.

There are alot of L-134 willys motors running around with this same type of repair.