DO NOT put the XJ axle on SOA with the XJ perches. XJ and MJ perches are also different distances apart.
You would bend your springs out if you did.
However, if you welded new perches in the correct location to install SOA, you're going to net about 5-5.5" inches of lift in the back. A lift this high in front gets very expensive, and there's no safe way to do it cheaply.
When looking for a new axle, since you're fine with getting an XJ axle, try to get ahold of an 8.25. They were used in the XJ starting abouts 93. They're a MUCH stronger axle than the craptastic Dana 35. 93-96 have 27 spline axleshafts, 97-01 have 29 spline axleshafts.