On a typical Holley metering block, that hasn’t been modified, the power valve is worth about 9 or 10 jet sizes in my experience. About 2 full AFR points.
I have used these numerous times.
Both as upgrades to std Holley carbs, and as the foundation for built-from-scratch new carbs.
The kit comes with 74/83 jets(PV on primary side), which works pretty well when used in combination with std Holley metering blocks for a 4779 carb.
Replacements for a 4779 are what I’d use for metering blocks when building new carbs.
The air bleeds supplied in the body are .035” HS/.070” Idle.
(The Holley 134-300 body comes with 72/84 jets)
I’ve had to tweak the air bleeds on a few builds.