paintpro does have a point. you don't have to use the whole rear end. that would eliminate having to change brackets, however, you would still have to do work on the axle tube ends since they will not be the same and, of course, you would have to remove the axles from your rear end you have, which means almost the same amount of work as using the whole thing. but if you're going to change gears anyway, this would be no problem.....
however, i think that disk brake kits are already available for your rear end type. maybe cpp has them or possibly ece.