I'll say that I like the disc on my 52 1 ton, but they are not necessary. I drove the truck for a few years with the original brakes and they always worked and I was confident they would. Now that I have disc I find my self stopping later and faster than I did with the drums.... not that that's a good thing. I plan to go fast one day, and then I will be really thankfull for the disc brakes.
If you don't change the gears or the HP stock brakes are great.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-