David,
I note you have had confirmed ignition problems. If I were you I'd steal a known good carb off of another car.... Yeah, you have my permission to rob it from you dad's car
Anyway, slap the known good unit on and see what happens. You might have multiple problems here, which is not a good time to take carb tuning 101.
You really need to take the time to sit down and educate yourself on the basic theory of the Holly carb. This will allow you to reason through the problem if it is the carb.
BTW,
The power valve has a little diaphram in it that the vacuum acts on to close it during high vacuum conditions. When you drive the car and accelerate, the vacuum drops and a little sping in the power valve valve opens the power valve to to supply additional fuel via a paralelle path.
Anyway, a blown power valve (ruptured diaphram) would cause a rich condition when in low load/ rpm conditions because it would then be open all the time.
Steven