Disc brakes on the deuce Rockwells is a popular conversion due to the availabilty of them, toughness, and ability to be swapped into other vehicles for offroad use. Generally you have two choices for brakes; Pinion brakes or wheel brakes. Stock drums are removed due to weight and the fact that mud will tear them up. Pinion brakes are not the best for street as the differential can cause some interesting things to happen at the wheels but for wheeling...theyre pretty much the norm'. Wheel brakes are ticket for big tires that are gonna see decent amounts of road time as usually the minimum is going to be a heavy 42" tire and they're only going to get bigger from there.
Past 'hands on' experience would have me leaning toward Florida as vendors would go and also definately check out Differential Engineering, and see if John Stazworks has any brakes in the works...one of those guys up north had some reasonbly priced brake kits a little while ago.
Also- discs would be cool on the deuce but it's gonna be some time and money. Is brake fade a question? Are there reasons for this option to be viable?