Whoa, I don't think that disk kit above will work on a 3/4-ton without also changing the axle and spindles.
The bearing sizes used on 3/4-ton trucks are different than those on the 1/2-ton, and I'm pretty sure that difference starts with the spindle diameter.
There is a guy here on The Stovebolt who details an 8-lug disk brake converstion and another guy over on OldGMCTrucks who has done it. A third guy, Mark, or ccpanel, who hangs on the yahoo groups truck sites is marketing a kit to do this.
But check those spindle diameters before buying the 1/2-ton kit, I don't think its going to work.
