Topo.Ranger
Adventurer
This XV-JP originally came from EarthRoamer with a Teraflex suspension and, while it was decent on a trail, I didn't like the pavement handling at all. In fact, all the flex seemed to me to make it scary on freeway-speed curves. So I wanted to change it pretty early on. The suggestion to change to the nth Degree, now AEV, suspension came from Scott Brady who had had good success with it when he had an XV-JP with 3.5 inch in the front, 4.5 inch in the rear.
A stock XV-JP weighed about 7K pounds, as did mine after the mods, so I can't tell you how my setup would work for a heavy, but still lighter, built up JK. For my truck, though, I don't believe I could have done better. Pavement and trail performance were both all I could have hoped for. Sadly, though, that's as far as my expertise goes; I haven't much experience with other options.
Good luck.
What I was leaning towards is similar to what you mentioned. 2.5" springs up front and 3.5" springs in the rear. Im hoping that will work. But thank you for that information.