Howdy Brando... I think your choice of gearing for the 33" tires is a good choice for the little 4-banger. Your ride came with 4:11's in it and about 28" tires.
I assume most here were considering you having a six cylinder in your Jeep.
The rear brakes only stop about 20% of the stopping load. So adding rear discs won't really add much stopping power.. UNLESS you also add more hyd pressure with a different master cylinder. So don't expect to stop your ride in LESS distance. Since disc brakes came into use the stopping distance hasn't been improved.. vehicles still stop from 60 mph in the same 160 feet as they did before.
If you need to stop more quickly you will need larger discs such as come on one ton trucks and more hyd pressure to squeeze the brake pads more tightly on those discs.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />