Restoring a 71 Vert

Hello new friends-

I'm restoring a 1971 Super Vert, and I'm having some engine trouble.
Hoping you find citizens will be able to provide some insight.

I've set the points and the timing...but when the engine warms, he
won't idle. If I manually choke the engine (by closing the butterfly)
he'll idle happily.

If I advance the timing by about 80 degrees (!!!) and crank the Fast
Idle screw in real far, he'll idle again, albeit a bit high. On the
road, though, he's all out of things to talk about at 35mph.

Adjusting the Bypass and Volume Control screws don't seem to do
anything. I've screwed both all the way in and he behaves the same.

Thoughts? I'm pulling the carb off this weekend for a thorough
cleaning.