I have the Fuji gsw 690 III. It's a fantastic machine and for my travel and landscape needs it's perfect. I would seriously consider waiting for the 6x9 65mm lens version if I were you.
If you don't mind me saying, it probably wouldn't be worth your while buying yet another 6x7 format when you already have a good system outfit. And personally speaking, the 6x9 and wide angle combination will be a better complement to your existing kit (I also have the mamiya 7II outfit).
Last but not least, and forgive me for saying, because I'm not familiar with your style, but THE WIDER THE BETTER! I'm confident that you would prefer the w-i-d-e-r option and that you would always regret not being able to get enough in the frame.
By the way, this link might be a source of both information and inspiration!