Mamiya 200mm/2.8 APO Tripod Collar?

[Conner999]

This is a long shot, but does anyone know of a tripod collar, regardless of make, that will fit the Mamiya M645 200/2.8 APO?

As an FYI for anyone with a set of calipers, a box of tripod collars and a fit of boredom, the required collar diameter (closed) is ~70.4mm (larger can always be shimmed).

Thanks