Hi mike, when I bought my m670 new back in '83/4 it definitely did not come with 67 masks. It came with 35mm masks only, and I also got 66masks as extras thinking I would never need a 67 mask. It also was not sold with a power supply either, but it is pretty useless with out it so I guess this one is sold with it.
I made my own 67masks with the help of some friends that have the right tool. It was based on the 66 mask, made from Aluminium sheet, polished and anodised black. I started with cardboard masks, not such a great idea.