Hi Atlas,
There does appear to be significant luster on this coin which I think should support a grade of EF-45. I don't think it makes AU-50, but you never know.
Carson City did produce a few branch mint proofs but I'm not aware that the 1875-CC half is known in proof. Certainly there are lots of proof-like and deep mirror proof-like CC dollars, so I expect some halves also exist with P-L surfaces.
I'll know more when I receive the coin. I wouldn't complain if it is P-L!