I had the same problem and symptoms with my 235. I went to an HEI conversion and set the timing. It now runs smooth with no missing and a noticeable increase in power. I was having a problem with the gap setting changing (per the dwell angle I was measuring with the engine running) when I initially tried to tune up the engine with the old points system. I have since learned that this can be caused by a worn distributor shaft. I don't know if this was the problem in my case or in yours, but the HEI system and new coil have certainly been a vast improvement over the old ignition system. By the way, I started out trying to adjust the carb as well, figuring that it was a fuel problem.
