The HG should match the head. Earlier heads have a flow director and need a gasket to feed it. Later heads are cast different with no flow director & use a gasket that directs cooling toward the exh ports.
I think the change-over was 11/84The difference that I remember (and is not visible on the 61010 above) is the 61010 had different waterholes at the rear of the head to feed the flow director that pointed at #6 exhaust.
Other than that, all 2F/3F HG look pretty much the same.