I really recommend sticking with the 5.13s. Many people on the forum run 5.13s and 35s with the 5 speed and enjoy it. Others run 4.88 with 35s and also are okay with it. 4.88 and 37s is going to suck on the freeway and be hard on the clutch.As I stand, Id really rather the 4.88`s. Ive cancelled order on the 513`s. I am looking into brakes. ZJ steering Ill have to research. Thanks.
I would recommend 5.38 if you had a front Dana 44, but since you don't, 5.13 is the highest you can go.
As for the brake kits, go with one of these kits:
https://www.shop.blackmagicbrakes.com/VANCO-Big-Brake-Kits-15-16-Super-16-and-17_c84.htm
They are very well received on the forum, and the owner is very easy to reach out to. I suspect the Super 16 or 17" kits are the better options in your case, but be sure to reach out to the owner.