The colour of the dial face is difficult to determine, their colour varied slightly over the production years and they are all faded now to varying degrees. Replicating the exact original colour via a printing process is therefore impossible. If pushed I would say originally the were a dark grey with a hint of green, although opinions differ depending on the individual's colour perception.
My 400f has non-original colour dial faces fitted, close to what I think the original was and nobody has ever commented on their colour. What they see is a tacho without a faded red line, clean glasses, nicely painted bodies and bands that have been removed/refitted without any visable evidence they have ever been apart.
