Thank you, ArchPhoto;
A simple adapter to fit the larger format is a good simple way to get the light sensing element into at least the center of the 6 by 6 film plane. That would certainly be a good quick way have something in operation until I can build my own multi-sensor element (with external switching between elements) or decide to "invest" in the genuine factory piece. There might be merit in looking into buying one from an overseas contact. I do have some acquaintances in Japan at this time. I wonder . . .