If you have access to a good welder and an equally good machinist, the 2-carb manifold can be altered to accept the Weber progressive carbs without adapters, but it would be an expensive conversion. I'm contemplating doing something similar to a single carb manifold for a highly modified 261 engine, to install a 2G series Rochester 2 barrel, or a similarly sized Stromberg carburetor. That engine will be close to 300 cubic inches, and Carb King and I believe a Stromberg 2 barrel for a Chrysler Corp. 318 would be a good fit. The cylinder head port design limits the max airflow, so putting high CFM carburetors on a stovebolt engine doesn't make good nonsense anyway.
Jerry
