There are at least 2 different Edmunds 2 × 2 manifolds, with very different plenum volumes, and perhaps 2 port sizes (216 & early 235, and late 235 & 261). All AFAIK have the Stromberg 81/97/48 3-bolt flange pattern. These are between 150-200 CFM each, and probably more than you want since all 4 bbls. open simultaneously (not progressively like the Weber mentioned above).
Picture?
