Holley makes a "truck avenger" carburetor for steep angles off road. Generally your best bet rock crawling is fuel injection and then you don't have to worry about it. The only problem is the cost of it.
You do have another alternative... use your jeep within its design parameters. If you know your jeep will flood going through four feet of water, then don't go through four feet of water. Its a simple solution that works. I used to own a WWII Willy's and I went everywhere in the field with it, and others BUT IT HAD ITS LIMITATIONS. Once I realized that, I used them to my advantage.
If rock crawling is what you want to do, GREAT but I would really consider saving up the money for a fuel injection system. You don't need your carburetor stalling going up a hill or coming down for that matter.