Steve. The MSD works perfect (I'd have to look and see what spring setup and bushing I used for advance)........
The Demon is outstanding. Its their 650CFM, ElecChoke, VacSec carb.....I'm extremely pleased with it. Plus, the carb just flat-out looks great also. I'm running the Holly "Red" pump into it (thats auto-regulated), and also added the Russel liquid filled gauge to make sure it maintained a constant pressure. Another nice feature on the BG carbs are the float sight glass for minor adjustments.
Never a "bog", and excellent response. It took a bit to get the 4-corner idle screws adjusted just right. With (4) there's plenty of fuel coming out at idle, so it does not take much at all in the way of turns out.
Bob