I had the same problem with my T-Bucket that I bought. It has 2 new Edelbrocks on a tunnel ram on a BBC.
You can download a carb tuning manual from Edelbrock.
That's a pretty big cam for the rest of your combonation as others have brought up. I think I would start with a vacuum gage and check to see how much vacuum the engine is pulling. Both your carb and distributor works on vacuum and the big cam doesn't put out much. As those carbs come from the box they need around 12 inches of vacuum to seat the rods against the springs. If vacuum is bouncing around at idle, you should be getting over rich mixture at idle. Edelbrock sells spring kits to adjust these.
Others have suggested changing to a Holley or Demon type carb. They still have power valve issues but they are easier for some to deal with. The Edelbrock can be tuned to be reliable but it may take a cam change to make it work. This might be the best solution. Something like the old 350 HP 327 has a bit of a thump to it and still is a lot easier to live with on the street.
I had to change the cam on mine to make it livable on the street.