One thing that did help on my 235 to improve top end response was to install a 2 barrel Holley/Webber carb from Langdon's Stovebolt. Then I was able to smoothly and consistently drive it at 3800 rpm plus, taking me to around a 72 mph top speed on a 4.56 rear end. That was only for bursts of speed. But I routinely averaged about 68 mph on the highway.
There's no way I could have gotten that kind of throttle response with the Rochester 1 bbl.
