If you have every single steering and suspension component in brand new condition and adjusted correctly and your brakes are functioning properly, 70-80 mph is not a problem. That is, unless there is anyone else on the road that you kill because you lost control for what seems, at the time as a minor bump or slick spot that causes you to lose control. These trucks ain't exactly agile.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission