Didn't see this thread till I was recntly looking for some dakota leaf springs for a cherokee, my buddy has a some coils from a zj, we sold the front 2 to a buddy yesterday, I beleive they are 4.5 inch lift coils, so on an xj maybe a 6 inch lift, you wont for sure need an SYE, I ran a 6 inch and 33's with no sye fine, when I went up to 8 inches it became a must.
Shoot me a pm if your interested or still messing with this.