I used Shawn Murphy at SMI in Huntington Beach for Bonneville and Circle Track Carburators. They are pretty specific and definately not "off the shelf".
seb - What...engine do you have that you think a normal "performance" carburetor can't help you ? Holley, Quick Fuel...both make very performance oriented carburetors, if you just pick the correct one ! Off the shelf, made for Roots blowers, made for "blow through" supercharged systems . With and without "annular boosters", down leg boosters, etc., etc. What's so exotic about your combination, that a properly designed, off the shelf carburetor won't work ? Curious... Mike