Ok, the backfire was timing. Fixed that, and plugged the vacuum advance into the carb base rather than the manifold. I know that they say to plug it into the manifold for an HEI setup, but I couldn't get the idle down that way.
The choke still doesn't seem like it's working, though.
Also, question still stands on the power valve.
I'm thinking the reason it seems to run rich is b\c I have NO emissions stuff connected whatsoever. That's another project in itself.
All in all, though it runs much better than it has since I've had it.