Back in the mid-1960's I ran a 58 Chevy 2 door sedan with a 235, 3 speed, and a 3.70 rear end. It had low profile 14" tires on it, standard for that model. I had no trouble keeping up with traffic at 65-70 MPH, and the mid-80's were not too difficult. With 3.90 gears and the same 1:1 high gear ratio in the transmission, a bone-stock pickup with a 235 should be able to do similar speeds because of the taller tires.
Jerry
