NY,
Like Vector 1 stated, a larger carb will work with the AirGap.
I have an AirGap on my 351W with .030 over and I tried a 660 Holley Street Avenger and it had a bad hestitation starting out.
I looked at the Edelbrock spec sheet for the AirGap and it recommended a 750 cfm carb for a 351W.
http://www.edelbrock.com/automotive_.../7000/7581.pdf
I put on a 770 Holley Ultra Street Avenger and it really made a difference. No hesitation at all.