Didn't find bolt pattern addressed in Carter book but found following information in case anyone interested ..
WCFB Carter CFM rated at 385 cfm .. doesn't look adequate for my needs, not sure AFB's made in small bolt pattern, Carter models have the following flow ratings,
AFB early (square-bore) 450 to 625 cfm
AFB late (square-bore) 400, 500, 625, 750 cfm
AVS (square-bore) ? same as AFB late?
Thermo-quad (spread-bore) ? up to 800cfm
Edelbrock Performer AFB (square-bore) 500,600,750,800
Edelbrock Thunder AVS (square bore) 500,650,800
Found 4G(4-jet) Rochester CFM's were 486,553 and 692 (online) .. couldn't verify small bolt pattern exists on these either, ebay seller said his 4-jets were not ??
Offenhauser tech maintains 4360's a good carb choice, will just start with those
Next question is .. ignition. Choices appear to be fix up my old Mallory 4lobe dual point, possibly retrofit with Pertronix electronic ignition, or get the small no-name distributor offering on ebay, since factory HEI is out the window with dual quad ... The Mallory does not have vacuum advance only centrifugal, not sure it is possible to change this or how overall advance is limited/regulated with this distributor. Or what the Pertronix upgrade does affecting this. Does anyone have numbers on it? I know I want street response and drivability with DQ and am thinking vacuum advance will be necessary.