So I'm new to Holley's. I think I understand the basic principles of the various circuits, but probably not as well as I think.

The power valve starts to open at it's vacuum rating, to richen the mixture when coming off of cruise to a more open throttle. Correct? General rule of thumb is the PV should be rated at 1/2 your idle vacuum. Mine fluctuates between 10-11, but was told to use a 4.5 PV. So vacuum has to get pretty low before it kicks in.

Could this be part of my hesitation as well?

And yes, I would use the same spring on both carbs!