Grading these dollar coins is not something I spend too much time bothering with. Plus, PCGS photo grade only has Sacagawea coins to compare to. When I grade my dollar coins I am just looking for obvious marks and where in the focal areas the marks are. Are they hidden in the hair or in the fields or right on the nose so to speak. I think a lot of the high grades of these goes to overall eye appeal as well.
So with your coin I see some noticeable marks in very focal areas. The rims look good which is rare. Lighting seems to be hiding a bunch of smaller marks so I can't get a feel for eye appeal.
From these over exposed pictures I would say better than average at MS64 without better lighting and ability to read the surfaces better.
You will see one pop with eye appeal. It's very noticeable. It will stand out from the rest very well. If it also has less then a few marks in the main areas than you have an MS66. The proof like ones are even more noticeable and very rare.
Thing is, grade really doesn't effect value very much for most of these. 99.5% of the time you will have MS65 or lower. The 1 out of 10 rolls you may get a MS66 and it's worth only a couple dollars more than the masses of regular above average coins but you will never know because getting them graded costs too much.
For me, I don't spend too much time on them. Pick the best ones really fast and move on.