There are dual masters made for the 1/2 tons that have boosters. They are made to fit in the original location, probably with a special bracket. They use what looks like dual chambers on the booster that are smaller in diameter. I don't know if they sell one for the 1 Ton.
My 51 a Ton has the original type brakes and they work very well. The one problem is that the back brakes are much larger and create a proportionally larger force than the fronts. This is not a problem on dry pavement but on a wet surface it can be. I have thought of adding a proportioning valve and I might do so because I don't carry loads.
