I'm not as familiar with Xj frames, but a reason not to do SR on a CJ is that the frame will crack. Frames on CJ's at least are not up to the stress of the solid mount on the front. YJ frames on the hand are better for this type of thing. The other problem is the tire tends to stuff into the back of the fender and you'll need a longer splined driveline to make it work. Now on an XJ you can design some of these problems away, but I dunno about the frame one......after all, XJ's don't have frames!
Do you research first, there are lots of guys running leafs on XJ fronts out there. I am a big leaf spring fan, don't get me wrong.
EZ