The primary boosters are annular discharge. This provides better signal and atomization. This aids on an airgap style manifold or the slant six with a Dutra or Hyper Pac intake.
Talk to Dan at The Carburetor Shop in Minnisota. The AVS2 500 CFM boosters should work.
The old AVS or Air Valve Secondary have regular boosters, so you need the AVS2 annular boosters.