Eric,
If you don't have a lot of mountains to climb, you could go with a newer transmission from the '62 era 235 and go with a higher speed rear end, like a 2.73 or 3.00. Your engine speed with go way down and your fuel mileage will do better, too.
Here's how I know: In the late '70s, I had a '50 Chevy coupe with a 216, 3 on the tree and whatever the standard rear gears were. At modern highway speeds the engine was wound tight and sounded like it was going to explode.
I bought a '60 Chevy 235 engine with the original 3-speed transmission and installed a Nova rear end from a V8 car, with 2.73 gears. I felt sure I'd need lower ratio gears, but decided to drive it like that for a while. I was so pleased with it, that I never changed the gears. The engine was relaxed at 65 mph and the mileage was better than the 216s ever was!
That's my experience...........
