RE: Is the RUBICON lifted compared to a stock tj.
Except for trying to squeeze a little more articulation out of it, a flexy chassis is pretty much useless. The Jeep will be more responsive to driver input as you stiffen that chassis a bit. The main benefit though is consistency, which isn't really a concern of a trail Jeep, but tuning of individual vehicle systems is useless if you can't expect the chassis to react the same way each time you hit the go pedal, therefore allowing them to operate the same each time.
Lots of people have different opinions on how to properly stiffen a frame. The absolute easiest method is to tie the rollcage directly into the frame. Ladder type bracing can be added easily, but you just want to make sure that you don't end up with sections of the frame being more rigid than the rest of it, as that will lead to cracks when you twist it up.
The 76 and later frames aren't really bad at all, but the later CJs still flex a little too much for me. When I did the axle swap, I added lots of bracing that tie into the shackle mounts, and I added a crossmember/Dshaft loop to the front spring hangers. I'll be adding the same setup to the rear spring hangers and a .125" thick rear crossmember to replace the torn up original. I didn't really want to, but the front frame horns were spread and twisted just a bit and I needed a way to pull them back straight.
