273 commando carb

1965 manual trans: 3853s
1965 auto trans: 3854s

1966 manual trans: 4119s
1966 auto trans: 4120s
1966 manual trans with CAP: 4121s
1966 auto trans with CAP: 4122s

1967 manual trans: 4294s
1967 auto trans: 4295s
1967 manual trans with CAP: 4304s
1967 auto trans with CAP: 4305s

If using an original Intake manifold The 600 Carter and 600 Edelbrock secondary valves are too large to open. If I remember correctly.
that is correct but only a hair. I doubled up the gasket under the carb, works fine.