You know, I have the 4.2 with K&N intake and a MPI kit, and with 31"s and 2.72 gears I can barely tell the difference between a sack of potatoes in the back or our popup camper (something like 3200 pounds loaded). The MPI kit gives the Jeep soo much nut... its unbelievable the before/after comparison.
Trust me, your making a good choice with the Jeep. Back in the day my Jeep did better off-roading stock than a lot of people with 3" lifts in trucks.
My advice is the usual, ask lots of questions, and when you take it for a test drive, drive it in good spots, test its engine power IE drive up the side of a mountain and see how well you can accelerate. Test 4wd at all speeds (mine rumbles at 55 for some reason) any noises are bad. besides stereo and engine. heh.
89 YJ with 258 bored +30
Mopar fuel injection kit
3.5" suspension lift soon to be installed