I've driven over 3000 miles in my 1950 1/2 ton in the last 18 months or so. Driving is equally split between highway and local roads. I've hit potholes at 50-55 as well and never had the truck act in a manner that caused me to lose control or make me consider the handling to be dangerous.
I would check the entire steering system with someone turning the wheel slowly while you observe each link in the system for delay/play/slop. How are the springs and shocks?
Certainly modern vehicles handle much better than 70 year old trucks but that doesn't mean that 70 year old vehicles are inherently unsafe or have loose, sloppy handling.
There is a front anti-sway bar available for AD trucks that is a bolt-on part (original equipment on panel trucks, I think). They are available from one or more of the restoration specialty suppliers. Perhaps that is something to consider installing. I have not installed one but probably will do so at some point.
The front shocks on my truck are Monroe OE Spectrum 33049 and the rears are Monroe Gas-Matic 5826. I have 16" rims and Firestone radials.
