I don't know what year ur XJ is, does ur T-Case have the short output shaft housing or the long one? If your's has he short one you shouldn't have any problems. The best way to know for sure is add the lift and then see if you get vibrations. I didn't have any problems till I got above 3" of lift. Then I had to Fab a SYE set-up. I've heard of people running 4.5" and taller lifts w/o any vibs, so its hard to give ya a definitive answer.
But 2" isn't that high, so you should be good. That's about as high as you can go without touching anything else. You don't need to change shocks, it shouldn't affect ur Caster enough to cause any problems, etc.
Have fun...