Well...?
Paul,
Usually I am very suspicious with the claim of "original keys" that some "aftermarket" sellers offer.
Our original keys surely show the "Neimann" logo (230 & 250 early's ignition key) and "Ymos" logo (all other keys), and those are NLA or only partly available from Mercedes Benz.
Even they use aftermarket or third market suppliers today for the key reproductions which you usually get at the dealer's shop.
So, I'd be really impressed if you could get fully original Ymos keys, especially the round one (letter K).
A picture would tell us more than a 1000 words ....
Best,
Achim