what CFM would you use here

well I thank you guys for the info here. it looks like I am gonna have to take the time and put the 4bbl. intake on it with a new 4bbl. I just have never dealt with one of those adapters but it seems like I would have some of the same problems I have now. Probably go with a 600 of 650CFM carb. what is the difference between a AFB and AVS. which would suit me better on a dual plane intake. I think there is an Edelbrock RPM on one of the 340's I have.