I try to avoid modified vehicles. You never know what shortcuts were taken, and the owners always inflate the price. Most modifications do not add value to a vehicle, and those that do tend to only add a small amount. The only time a big-ticket modification will add value is in a professional-quality engine swap that isn't a small-block chevy, and even then the swap will cost significantly more than the increased sale value.
$5000 is pushing it for a mint stock Niner. I'd say the modifications push it down $1000 on their own, just in terms of what I'd spend. The salvage title, however, knocks at least 50% of the reasonable sale price off. If it's in excellent condition otherwise for $5k but it's salvage, it's a $2k car. It's incredibly difficult to get a unibody back to factory after it's been tweaked in an accident, and most shops don't bother to get it close enough. That'll cause problems down the line, I can almost guarantee it.
All in all, I'd look elsewhere. This Jeep is nowhere near worth what the seller wants, and it's probably a pile of problems, between the wreck and the modifications.
1997 Grand Cherokee Orvis Edition
1998 Grand Cherokee 5.9 Limited
FUEL ECONOMY IS FOR LOSERS