Hey Mike,
I went through the same ordeal on my 56-235...rebuilds, float adjustments...more float adjustments......wound up buying a "rebuilt" Rochester from a local parts house only to find that it was improperly assembled at the plant and the throttle shaft was excessively sloppy. At $109.00 this was no bargain.
I called Tom Langdon at Stovebolt Engine company and he suggested converting to a Holly/Weber progressive 2 barrel. This is a rebuilt carb, adaptor to mount it on your stock intake, a linkage package, electric choke conversion kit and he offered a polished breather kit as well.
The installation took about 30 minutes, the carb has performed flawlessly. I get better acceleration, no flat spots, better mileage than with the Rochester and the only adjustment I had to make was to set up the idle a tad. Bolt it on and forget it! Time to enjoy driving your truck. The total for the entire carb setup was $117.00. The air cleaner was a bit more pricey at $45.00 but it's a beaut!!
I am continually reading posts from folks that are trying to salvage their ancient, ill running, leaking Rochesters. Granted, the Holly/Weber doesn't "look" stock but they function GREAT! If you're interested in a carb that will make your truck drivable, I'd give Tom a call. He's always willing to answer questions and his product is worth every penny. This is not an endorsement...it is a fact. I hope this helps you with your Rochester problem.
