No matter what I would replace the 7.5 with the 8.8
read this through ORR 8.8 Discussion
with the 7.5 turning 33's or 35's the power would find the weakest link and destroy it, whether it be the t-case, f.driveshaft, rear end, etc.etc.
If you want 35's I would look into the chevy spring swap possibly or just cut out your fenders more. I personally and still finding a way to lift the front end more because I am planning on doing the chevy spring swap as well.
The second post by Bob (rwenzing) will tell you what gears you have. I have the 8.8 with 3.73's and 33's. If you have less then 3.73's I would think about re-gearing for sure. You might get lucky like Livn did and find the 8.8 at the junkyard with the 4.10's already in it? Best of luck, let me know if I can help out further, Blades