Sorry for the late reply, went for dinner. Was not sure I can post eBay links so I just gave key words for eBay search. The auction is over and the lens was sold for USD 7,100.
Last week there were 2 grey IIIcK's, one with a grey body case. One had a verified IIIcK sn and one did not (the batch after). They had the K curtain and wartime IIIc body but... The one with the correct sn (no case) went for USD 1500. A great deal if real.
It looked to shiny when comparing to the one in my hand (I robbed from one of my friend).
The red markings look orange.
The infinity tab button should be brass. I see tiny chips come off exposing silver.