Very nice, congrats on the new carb and getting it running. So what RPM does it idle at now and how does it drive? Yes, timing could be why it stalled out. Factory timing specs are 8 degrees initial; these engines perform better with more advanced timing.
Vacuum advance is a hotly debated subject...such as Holley carbs vs. Edelbrock. Manifold vacuum is the way to go (the one that sucks at idle). Read this article, its a little lengthy, but it was written by a GM engineer who helped develop it and explains it very well (I researched him, he's legit). I'll believe the guy who helped develop it over anyone else.
https://www.google.com/url?sa=t&sour...qW-jLv2NSpbyTi