The Makina is a great camera. The main failure with it concerns the meter, which is a built-in flaw of the construction. The meter is not too useful anyway IMO.
Sometimes I read about the transport mechanism which was apparently up for improvement in the 670 which followed the 67. Key is that the camera was handled with care.
I had a 67 which worked and it was a pleasure, very sharp, nice saturation. Only downside is the shutter release: it does make you move the camera downward, even if ever so slightly.
If the price is not different, I would now go for the Fuji/Bessa 670. For what I've seen, very nice camera, bokeh no better or worse, and it will be 30 years newer.... And you have the choice between 6x6/6x7, Plaubel is only 6x7.
Plaubel do still service their old cameras, but at a (substantial) cost.
I have heard warnings about repair of the Mamiya 6 because there are no longer parts available. Not sure how true this is. You may want to ask a local(-ish) repairer of repute if s/he has any parts, etc.
BTW, it's not a rangefinder, but I was surprised as to how little different in size my Rolleiflex was compared to the Plaubel.