I don't believe that there is an adapter for Mamiya to V backs, there was an adapter for Sinar backs so maybe it's possible. You will need to get a "V" back for best focus; Leaf, Phase One, Sinar and Hasselblad all made them. Even a Hasselblad "H" back will NOT work on a "V" (500 or 200) series body.
Best regards,
Dave