Wheel well opening are tight, and are a main reason larger tires can't be fitted.
A 3" BL is very do-able. I have a Calmini GV 3" BL, but requires a new strut truss, making the kits cost too high.
Losing the shiit-on-the-fly ait diff is not for the weak of heart. Losing the soda can front housings is a costly endeavor. Anvils don't fit GVs or XLs, so finding steel factory units is the only answer.
Manual GVs and XLs can't use crawler gear sets.
The GV's rear axles are anemic. The shaft is thicker than a D44, but pencils down to the puny 1.08" diameter 26 spline. With low gears, crawler t-case and a locker, they snap off rather easily. XL rear axles are beefy, but no locker app other than welding is available.
The 2008 XL7's 3.6-liter V6 DOHC engine (252 horsepower with 243 lb.-ft. of torque) would be REALLY nice, but seems difficult to swap in. I'd rather it in my Sammy.

I did some impressive stuff in my GV, and quite a few trails in Moab that are considered "hardcore", but it's still a grocery getter. Currently, its getting ready to go SAS to bring it to the next level.
but if I was going to build an IFS zook again, I'd pick an auto 16V Kick over the GV for the simplicity of it.