Wow! Nice 340 build! These Edelbrock carbs are ok for a stock to mildly modified engines. Your 340 with 7-8 InHg at idle may be too much for this carburetor making it difficult to impossible to tune. Was the cam installed with a degree wheel or "straight up"?
I agree the Eddy carbs are not tunable , change the carb tune it in& the problem will go away
I like the proform carbs , best bang for the $$ spent