Edelbrock part number 1020 was for the size 3 bolt pattern.
Weiand part number WC-101-PG I think was size 3.
I do not have catalogues for the other companies.
It was common "in the day" for the aftermarket manifold manufacturer to make the manifolds with the bolt spacing for multiples of the original carburetor size (regardless of if the engine were over-carbureted). That way the customer could order additional units of the original carburetor.
Jon
