I think it can be done without replacing the mast rotation pivot. It is a bit hard to explain without pictures but I am thinking of a piece of curved of 1.6mm stainless that can be riveted to the bottom front of the mast. Welded to that would be a hinge part which matches the other half of the hinge attached to the beam.

1140 Gadfly
1434 J.I.B.E.
1727 Atreus