First Welcome.
Second- the conversion is not that hard, but does require a front axle, transfercase, transmission out put (easier to replace transmission from what I have read), front and rear drive shafts. If you can find a wrecked 4wd or one with a blown motor it will make the swap easier since it would have all the parts. If you could find a 97+ you would get the stronger U-joints in the front axle, and possibly a 8.25 rear axle. Any year XJ would work, as long as it is a 4wd. I looked at buying a 2wd XJ a few months back and I looked into the conversion, but I found a good deal on a 4wd so I bought it.