My truck is a 52 1/2 ton all stock for the brakes. Got lucky and a quick pass with a hone cleaned all the wheel cylinders and the MC. Worked great. One line fitting needed some attention but when that was fixed I have had no problems at all. So no added valves or any thing else. I did get to do the brake shoe adjusting shuffle for one long afternoon. After that all has been fine. When my pedal does go down a bit I readjust and it works great. My brakes are Bendix not Huck so I can get parts local. That is nice. Your truck is bigger, 3/4 ton long bed? Parts for that are not too hard to find. But I have not worked on many of that model and could be missing something. Others will correct me if I have misled you I hope. A quick stop from 60 MPH will keep you focused for sure. But after the fist wiggle it is stable. Helps when you know it is coming. I suspect I still have one shoe just a bit looser than the others.

Steve H