I did the torsion bars on my Sierra and was happy with the height improvement but hated how the front end was "super sprung" whenever I went over a bump. Don't get me wrong, I wouldn't reverse it if I were given the opportunity, just learned to take it slow over speed bumps. The difference in the torsion makes the front end PUSH down over the slightest bump. As for the rear diff swap, you may want to keep a drive shaft issue in mind. I went from an 8" to a 9" Ford rear end many years ago and found out that the distance was different (longer yoke on the 9") and have to have my drive shaft cut and balanced. Hopefully you won't, but a heads up regardless.