It's better, but not EFI.
You now have 2 A:F setting: NA and boost. It gives the same enrichment at the opening pressure of the PCV as the maximum boost - but obviously full boost requires more fuel since by definition a carburetor does not sense a change in air density, only in air speed. Some part of the fuel curve is compromised. For a race car the difference may not matter - the mains give NA mix and the PCV adds whatever you need for full boost. For a street car this is more difficult.
What would be nice: a second boost-referenced PCV, even if it's an external circuit-in-a-box. A Snow or similar could inject race gas (to keep it legal) proportionate to boost, but $400...
You can get closer if your ignition allows proportionate retard on boost, but I'm guessing that most blow-through are normal ignition.