I have rebuilt a lot of carbs. I like doing it. The only time I've ever had an issue after rebuilding a carb was when I rebuilt my Rochester B. In fact I built two in a row and neither one runs "right". Don't get me wrong, after the rebuild the truck runs a LOT better, I can brake traction with these big old 30 inch 10 ply tires and the old 216, but I'm always tweeking it a bit to keep it running decent.
That said, I would never pay for a Rochester B, rebuilt or otherwise. I've got eight of them now and every one of them was free. If I'm going to pay for a carb, I'm going to pay for a Carter (as soon as I'm educated enough to know which one to get).
Now that I think of it, you might want to turn your idle mixture screw out a couple more turns and see if that makes a difference. After I rebuilt both my Rochesters neither one wanted to start with the screw turned out one and a half turns, and when it did I could hardly keep it running.
