I had a bit of trouble with the Carter AFB 500 where the pump shot was a tad too much. Read those plugs, and see what's going on.
The as supplied Edelbrock jetting will be mighty close, if not right on.
Did you go with a Performer or the AVS? If the secondary air valve on an AVS opens too quickly, you will go lean, so make sure the secondary isn't opening too soon. That may be accompanied with a WOT bog if such is the case. Set up right, you should be able to leave the tree on the floor, and the transition as the secondary opens should be a smooth increase in power. If it encounters a bog, or has a sudden change in power, the mixture isn't right. It indicates the primary is too lean if the power bumps up violently as the secondary opens. With a bog, the secondary is opening too soon, or the secondary jets are too lean.
While the butterflies open mechanically, the secondary air valve is operated by air flow. It will not open more than the engine can breath, unless the counterweight on the Performer series air valve is too light, or the adjustment on the AVS air valve is set to open too soon.
You may find that the metering rod springs aren't right. What color are the springs that you are using? I'm using the stiffest springs I could find for the AFB to bring in early enrichment of the primary main circuit. The stiffer the spring, the "Deeper" the enrichment vacuum point is.
You may also notice a pop when lifting from WOT. This happens when the metering rods are pulled back down by vacuum during a transition from hard acceleration to partial throttle. It corrects itself as the metering rod springs overcome vacuum again, but a brief lean condition can occur. This is bad news for high compression engines at high engine speeds, as high speed detonation can take place and parts start taking damage.
Timing is going to be an important part of your equation. If you have a dial back timing light, you can map your timing curve and report back on what you find. To get a good map, disconnect the vacuum can and plug the ported vacuum.
You're not going to want to run a stock timing curve. You are going to want less mechanical than stock with a 4bbl, and your going to want it to "Hop out" fairly soon. Somewhere a bit above idle.
If you can get all in before 3000 rpm, that would be best. Try to limit total timing to 30 degrees or a tad less with the vacuum can unplugged. If your getting more than 30 degrees of base+mechanical timing, that may be part of your issue. Time for a governor change. At high throttle settings there shouldn't be any appreciable vacuum advance coming in, so it should not be part of the problem your describing.
It sounds like you went pretty radical with your build, so tread lightly till you get things figured out!
CJ