Find a older Chevy running a 465. Call advanced and get a bell housing to mount that iron duke to the 465. Get some 10/14 bolt axles with a 373 ratio and you will be golden.
The little motor does not put out much power. But, with the 465 behind it you will have a impressive level of torque to wheel off road without worrying about breaking stuff.
On road the 2.5 will give you decent fuel mileage. Just don't expect it to have much power at highway speeds.
I have had 3 Jeep 2.5 and 9 Chevy 2.5 engines. I like these engines although they are getting harder to find. They are really tough to kill and are easy to work on and maintain.
Just don't try to make power with them cause it is just not worth it. Use gearing to make power and you will have a very reliable/capable rig.
Just my 0.02