AVS2 carb tuning. Anyone with experience out there?

I have owned a dozen carter /edelbrock carbs over the years and they have always worked great out of the box. This one (1906 650cfm) has a bad stumble when you mash the gas. Pulls hard once it recovers. Basically you have to ease the pedal into the power mode transistion or the engine falls flat.
Its basically a stock 73 340 that has been freshened with new bearings, rings, valve job, etc. Got about 1500 miles on the rebuild. Upgrades include air gap intake, TTI exhaust, and thats about it. Cam is a comp with specs comparable to a stock early 340.
Trying to use the calibration chart that edelbrock provides but im a little confused with it. I did try swapping around the step up springs first but that didnt seem to help any. Right now im one stage rich on the chart and honestly it seemed to run stronger with the factory calibration. I did not change the secondary jets and now im thinking I was supposed to.
I was thinking about going back to the stock needle and main jet with the orange spring, and stepping up a size or two on the secondary jet. Will this help my transition stumble from the primary to secondary?
I have moved the accelerator pump to the heaviest setting. I have also tried adjusting the secondary air door all different ways. I have not found any instruction on how to properly set the tension on that air door.
On another note, is this 650 big enough for my 340? I do have an new 800 cfm AVS sitting on the shelf I could try but I really think the 650 should be sufficient for this engine.