Welcome to CHR. Sounds like you've got a great combination on the engine build. Cam spec are reasonable as are your gears and stall speed (I really like the Vortec heads) and your vacuum is pretty good as well.

My first thought is that you you may be rich on the primary jets/metering. The Edelbrocks are a bit rich out of the box and if you had a 1406, I would point you to their (Edelbrock's) web site for the instructions on how to diagnose and then replace the jets/metering rods. I'm assuming that you have a true "AFB".

While I suspect that your Carter may be a jet size bigger than it needs to be, a quick check can confirm. If you have a good shop near by, they can sniff the exhaust and tell you if that's the problem. I'd try that first.

Others will chime in, I'm sure.

Again welcome to CHR,
Glenn