I can understand your confusion.
I have been looking at price guides and E bay.
The price guides I have looked at do not list
anything for satin finished coins.
Looking at E bay I see some of the same coins
slabbed by PCGS, some had "SATIN" heading with a MS-69
grade and some slabs had "SATIN" heading with a SP-69
SP-XX grades seem to be for satin of matte proof finished
coins. I have not seen any guides give prices for SP grades
Maybe some other members know of a guide showing satin finish coins.
As for your inventory. I some what agree that to grade your raw coins with the higher grades (MS-67 and higher)
could cause confusion for a future seller.
In my experience for a coin to be sold at a higher grade
it is when it is slabbed by a top
TPG.
I have seen many experienced coin collectors use terms like
MS-65+ (plus) for business strike coins they think might fall into the higher grades.
I would also say that most satin or matte proof coins,
when sent into
TPG's seem to come back SP-68 or SP-69
at least that is how it has been with the coins I have sent in. I am sure I would not put a lower grade on the coin you have posted. Saying that coin is a 63 or 64 coin
would be like saying something is wrong with it. If kept
in that condition putting a lower grade might be more confusing .. might be better to not grade it at all.