Panic,
I would say that speed is not a concern, rather torque/power. With the old 4 speed and rear end, even with 17" rims this will never be fast. But years ago, when I drove it down here from Champaign, IL it ran at 55 with no problem. And with the low 1st gear, it will pull anything.
Tim

I am currently digging back in to a 1953 3800 (one ton) with a nine foot bed. I've owned it since 1979, and drove it until 1982 (or so). My wife got me involved in restoring it back in 2002, got the body removed and the frame redone, then things came up. Now I am retired and starting again. If anyone is interested I have photos on Imagur ( https://timwhiteblues.imgur.com/ ). I live way back in the woods in the Ozarks on 40 acres at the end of a 2 1/2 mile private road.

Tim