Welcome to jeepforum.
Assuming it's not excessively ate-up with rust underneath, you've got a great base vehicle to work with and a wealth of aftermarket parts support as well as tried and true adaptations of readily available junkyard materials. Your build can be as complicated and costly or cheap and easy as you want to make it, while still being great reliable transportation on and off road.
I'd recommend this thread for starters in getting some ideas on where to go with it. http://www.jeepforum.com/forum/f11/budget-builds-what-junkyard-parts-will-fit-xj
G'luck with it and maybe I'll see ya on the trails one of these days.