Daytondigger,
I've got a '51 one-ton with 5.14 gears and go down the road as fast as I want to go with the old brakes and steering. Besides rear end gearing, tire size controls the rpm at a given speed. I got some 17 in tires at Carlisle on the old split rims that have a 33 inch diameter and (at present) a '48 235 splash oiler that gives me about 50 mph. Fast enough for an old guy in an old truck.
PA Farmer