manifold vaccum for vaccum advance ?'s

I would be leaning it back and get a good idle speed without vacum advance with your 34 total and try a test drive. Hook up the full vacum advance and see how much the idle increases, if it does get idle down and if it is still popping I'd be looking at the distributor not the carb.
Do you have another distributor to try?

Good article: [ame]http://www.corvette-restoration.com/resources/technical_papers/Timing101.pdf[/ame]