the 2.6 I4 is usually the head gasket offender. if you keep it maintained and you keep it from overheating, you will be ok in the head/head gasket department. it's not a terribly hard job if you are somewhat experienced wrenching, and this site has all the tech you would need regarding anything under the hood. one thing to look out for is although you may find a good fixer upper w/ a blown head gasket, lots of times the head cracks with it, and that might not be something the owner could tell you right off the bat. AMC makes a great replacement head.
I've had troopers with the 2.3, 2.6, 2.8, and 3.4 (replacement for 2.8). The 2.3 got the best mileage, the 2.8 was plain ok (not that much power but enough, and not so great mpg), the 3.4 is way fun but not great on gas, and the 2.6 is probably my favorite. Enough pep to get going, upgradeable enough to entertain yourself, bottom end should last you a gooood long time, pretty good milage (high teens to low twenties depending on driving style and conditions). Maintenance is key to longevity with any of them.
It shouldn't be hard to fit whatever tire you decide on. I ran 35's w/ no lift--a lot of fender cutting and pounding of the firewall, but it's doable. My wheels were standard 3.75" BS 15x8 steelies.
The trade off you may find yourself having to make is wheel backspacing: too much and you are rubbing the frame, too little and although you'll have a wider stance, your scrub radius will increase and you'll be rubbing the firewall and possibly the fenders in front of the doors.
If i was going to run IFS and fit a 33+ I would probably go with a small body lift and a small suspension lift. a little more ground clearance, and the body lift will allow you to use all the uptravel you are left with after the torsion bar crank. If you go all the way up to 3" w/ the suspension lift you are left with little to no droop in the front, and terrible cv angles. I'd swap to a one-piece rear driveshaft, manual hubs, regear the case, the axles, or both, pop an aussie locker in the rear and make some rocker protection and maybe bumpers. throw on a winch and you'll be ready for just about anything. <img src="/forums/images/graemlins/cheers.gif" alt="" />
