Very interesting. I gave it a 66+ because of the first photo and what appeared to be marks on her lower chin but your photos shows it different. If that's the case, this could very well be a 67 then. Edit: You know, if what you say is true and there is only one mark on her chin, I'm going to go out on a limb and say MS68 instead.
There was only one significant mark on her chin. There was 2-3 other tiny ones visible only under magnification. MS-67 is the max for this coin, and a 66 would not surprise me.
After seeing the additional images, I could see this getting a 66+ with a shot at 67. It is a real beauty and a great snag. I'm jealous.
I had to check some auction results when you said that 67 was the limit, There are a few CAC'd 67 that have more marks than yours. Pretty coin!
I recently sold a 1881-S MS 67+ CAC that had more marks than this one does, and the reason I said maybe MS 68.