Tarvin, if I was going to go that route, I would be running a proven nimble VW TDi engine. Look at what that engine has to push around. A 4500 pound sedan (assuming 2014 Jetta which I own) with more than enough power and performance. And it would be much lighter in the engine compartment than any mopar motor. There is a thread on TDIForum where a guy put a TDi in a Gen 1 Jeep liberty with great success. Even keeping the jeep 4wd.
TxStang, as much as I know it would be just fine with a single pipe exhaust system (as all my jeeps run 2.5 inch Flowmaster with High Flow Cat), could you imagine a dual exhaust manifold with Siamese 2 inch or 1.75 inch exhaust going all the way back. And if I want to be really creative in the end, relocate the fuel tank and bring the exhaust out the middle of the rear.