S&Ws were widely available at the Rod & Gun Clubs in Germany in the 60s/70s/80s, maybe still are for all I know. Anyway, they sometimes had German, or other, proof marks and sometimes did not. No rhyme nor reason to the extra proofs as far as I could determine. I had a M14 with them and a 27-2 without. I would assign no extra value at all. Some here might even devalue it with the extra proof stamps. Is it a 14 no dash or some dash number? Might pay a little more for a no dash or a -1 assuming it still has the original diamond target stocks. Pictures would help.
It will be a good shooter though, and if in really great condition $900 might not be a terrible price. If it shows some wear I'd think somewhere between $700 and $900 might be right, where I shop anyway. I'd probably have a tough time shelling out $900 for one.
Jeff
SWCA #1457