If you're looking for a portrait camera in 6x7 that also excels at landscapes, you can have a look at the former king of that genre, before the Mamiya 7II took over, and that is the Pentax 67 system. The lenses focus close, they have a beautiful look to them (I am always in awe at the images I get with my 105/2.4 and 165/2.8), and the whole getup will cost you a good deal less than a Mamiya 7.
I don't know of any professional (well-known) portrait photographer using a Mamiya 7. Everyone I am aware of who uses 6x7 for portraiture, and either shot, or still shoots film is using an RZ or a Pentax 67 of some sort (Bruce Weber had/has more than 10 of them, my father had 3 or 4, and it was in the stables of many other fashion photographers' equipment, alongside the prettier Hasselblads and Rolleis)
Also, all that nonsense about shutter and mirror vibration with the P67 is bullshit, I've never seen it in my negatives or prints from the camera, and the only situation I can imagine it being an issue in would be if you were shooting on a tripod with a cable release at a shutter speed like a 1/4 or 1/15 of a second, without using mirror lockup. If you encounter issues outside of that, you probably need the camera serviced.
