The Rancho add-a-leaf will give you pretty much 1.5 in the rear, a little more until it settles. I got mine from Auto Alliance, cant remember how much but it was pretty cheap and they delivered it the next day. You do need someone there though or the courier will take it away again as I found out.
Bear in mind the sport is already up 1 inch so effectively you'll be at 2.5 inches and may get vibes although most dont.
I'm also interested in the block option as I'm thinking of taking mine to 3.5 allround but want to initially do it as cheap as possible to see if I get vibes that cant easily be cured, so far I have none.
If nobody knows for sure I think go-jeep has the dimensions of the spacers for an XJ on his site so maybe some measuring is the best way to find out.
If not I may be able to check tonight as I made a template of mine before I put them in incase I wanted to hack up a chopping board for a little more lift
Cheers
Steve