I've got a few questions about lifting my xj. I went with the cheaper route and bought the superior suspension 3" lift, it came with 3" spacer front and 2" shackles for the rear. Already got longer shocks. Do I need a longer track bar? What else should I get?

Your title is misleading. I assure you, yours is not the the first XJ to be lifted. A quick search should turn up an over abundance of information for you.

Spacers and shackles are easy to swap in. I suggest you throw them in and see what happens. It may be fine, it may bring issues to light. Absolute worst case, it acts crazy, you yank the parts out while you source the necessary parts to sort it out.

I have a 3" lift on mine and I am still using the factory track bar and mount with no problems.