Unless you have something with more torque that the original 235 six, you will be extremely disappointed with the performance of a 3.38 rear end. Even if you never intend to haul something heavier than an iced down Yeti cooler to the local car show, you'll end up with an anemic ride that can't get out of its own way.
I put thousands of miles on a 1958 Chevy Del Ray coupe with a 235, a 3 speed, a 3.70 rear end and low profile 14 inch tires. It had no problem whatsoever running 70 MPH or more and not only kept up with, but outran the majority of the traffic I encountered on the highways of Tennessee. There's no reason your truck can't run 65-70 MPH with no modifications whatsoever.
Jerry
