Carb choice

holley 390 or 500 (4bbl) offers more adjustability on the secondary side (vacuum spring rate) but the Edelbrock should not stumble when punched as the secondaries are not really open to full vac as the secondary doors are not pulling open yet. Could it be a pump shot issue? Smaller shooter will draw out the pump shot over a longer time where as a larger shooter will literally "run out of gas" faster. you could also try and use a different hole in the linkage. I believe the closer hole to the pivot is the larger shot. the 2300 may work but I have heard the 350cfm version is all you really need. Do the math for your combo.