The heads would tell us a lot about the engine. My guess (based on the 4 bolt) is that you have a 3/4-1 ton truck engine. That being the case, in stock trim the output would be closer to 190 HP (rated at @ 4,000 rpm) with the torque close to 300 foot pounds @ 2,400 rpm.

Probably a dependable engine for your Jeep. In the event you wanted a mild performance increase, you could add some headers and an after market intake and carb (if your state law allow such). Big gains would require big dollars as the block and crank would be the only things you keep and work up from there.

You didn't say what you're after - but for a good daily driver, with a set of headers and some free flowing 2-1/4" exhaust, it would probably prove to be a great rig.

Good Luck,
Glenn