I did not realize we were talking about a 1 ton. I thought, or rather assumed, we were talking about a typical half ton. The fact that it is a one-ton opens up a whole new can of worms. I am a serious inliner type guy, but I would not recomend a 235 for a 1 ton truck that was available with an optional V8. I'd look into what V8s were available in that truck in 1961, and try to stay period correct. Remember GM introduced the 327 in 1962, and believe it or not there are more 348's and 409's sitting around in dark basements and garage corners than one would think, and either would be pretty cool. You can bump a 283 to 250 hp pretty easy and that was almost certainly an avaible option. Steve's nail head suggestion would also be period correct and way cool. Of Course, if you insist on keeping the 235, that's not a bad thing at all, but you are going to spend some serious bank on getting the kind of HP I think you are going to want. It's possible to bore and stroke a 235 so it comes up 260 inches, and then go from there with head work, cam, dual carbs, et, but remember, we spell custom rotating assmbling like this: $$$$$$$$$.
Are you beginning to understand what I said about dozens of paths to travel?
Boo
