I daily drove my 52 GMC 3/4 ton with 4.56 gears in back, and I had a 235 in mine too. I agree, I tired of the wheezy power levels, but I could get up some speed on it, even with 4.56 gears.
With the original 1 barrel carb, I could only manage about 60 mph, but once I changed it to a Holley/Webber from Langdon's Stovebolt, I could hit about 72 mph top speed. It made a difference in power, torque, and mpg.
I am now almost done with a 350 swap in mine. There are some problems to overcome if you choose that route. So if you're looking for ease of reaching your goal to be able to go faster, I agree with others. The 235 can be improved to run better. Look to getting a tall rear end in it first. Then consider a 2 barrel carb swap and split exhaust next. If you still don't like the power level, then if you can find a 292, that might be an excellent upgrade. I ALMOST went with a 292, but when it was sold out from under me, I decided to drop the 350 in that I already owned.
If you really want to get exotic, a Cummins turbo-diesel might fit even better than a V8, and even though it would have a similar rpm band as a 235, it would make tremendously more power. I think that would be a very cool swap, and would be interested in hearing from someone who's done that.
