Wiring on these older Jeeps was fairly simple. I'd get a wiring diagram and study it. You may decide you can make your own harness and save some $$.
Also, if the drivetrain is stock, I think it may have 5.38 gears. That's like 45 MPHish at 3000 RPM with 31" tires. Keep that in mind if you decide to swap engines. Me, I enjoy taking my time when I'm driving the Jeep.
"Work hard, rock hard, eat hard, sleep hard, grow big, wear glasses if you need 'em."