A-body K Members

The 2-barrel manifold was used on the '76 "Feather Duster"

No. The Feather Duster and Dart Lite had an aluminum 1-barrel intake.

and '77 and newer "Super Six".

Yes.

It also was used in the Assie version of the Valiant.

No. The 2bbl setup used in Australia, South Africa, and other countries used an intake different than the US "Super Six" item shown here.

Your one carburetor, shown rightside-up, appears to be a '66-'69 273 or 318 item; with the 4-digit number off the blue tag it could be identified more specifically. If the other carburetor has a tag, it could be identified, too.

Your exhaust manifold doesn't go with the Super Six intake; it's a '70-'72 item not compatible with the Super Six choke, but sometimes in demand for other reasons (and a № 1232 electric choke kit makes it compatible with the 2bbl setup, though you have to make a blockoff plate and gasket for the exhaust manifold's open-hole stove).