Carb tuning, larger accelerator pump nozzle?

Back in post #39, I suggested reducing the MAB size to bring in the main system earlier & gets more fuel into the system. Because you could have a lean 'hole' from the idle cct declining & main system starting.
The original Holley book, written by Holley engineer [ later VP ] Mike Urich says this: "Decreasing the bleed [ mab ] size increases the pressure drop across the main jet to pull more fuel through the main system, giving a richer mixture".

Note that early Holleys did not have removable E jets & ABs because they worked just fine with fuel jet changes.

You could also look at increasing the size of the PVCR &/or power valve to a lower number. The PVCR supplies the additional fuel in the main system, when the engine is loaded. The PV controls when the extra fuel is added.