600 CFM, all I need. Check my math!

Have you checked your fuel pressure? It should be best at about 5#. Most mechanical fuel pumps will go as high as 10# and will force fuel past the needle and seat causing a rich condition that can't be tuned out. A friend found that out on his Super Bee with 2 different engines, 2 different carbs, and 2 different fuel pumps. A simple pressure regulator fixed the problem.