After many attempts at sealing, and having stay sealed, my own T Ford manifolds, and fitting new exhaust manifolds, I have formed my own style of "solid individual flange" type gaskets. You will see from the cutaway photo how they are formed within the manifold and block, thereby not allowing any gas to escape past the outside of the flange. They are made with the flange left open, so once they are heated and re-tensioned to 18 ft-lb on the studs they will form over any irregularities which may exist on either face of the manifold or block.
Another major advantage of this gasket sealing ring is the ease of fitting - no multiple parts to be juggled whilst trying to hold it all in place.
This is a set of 6 formed copper manifold gaskets / flanges. They are sold in a pack of 6 to be fitted now or carried as spares for later. These gaskets have also been reported extremely successful on mid-1920's Essex and Veteran Little.