GS - My 780 Holley will be in a box in your driveway by the time you get home from work today. I was talking with another Holley "fella" and of course he has no aversions to them other than to get the most (Barry Grant level) it requires some work. He said I'd be your best friend if I would talk you into a Speed Demon for $350! He also believes it is most likely your power valve which is causing the problem. Let me know if the "spare" carb works - oh, for some reason all my spares are Holley's and the carb I run are Demons.
My 780 is a mechanical advance - is that ok?