One side goes to the choke housing, I assume you are talking about picture two goes to the choke? The other line from the other side, all it is will be a filtered air supply and not hooked to a vacuum source. I am not sure if the 2 and 4 bbl had them hook to the air cleaner or if there is a port at the top of the carburetor for it. It the port for it is on the carburetor it would have to be on the side near the top. Has to be above the venture of the carburetor or it would have vacuum. I would have to look at the manual and see what it says but it should say where it hooks up at.
It is only filtered air supply to avoid sucking dirty air into the choke. The choke side will draw the filtered air through the manifold.