The original colors were black on the outer background, and a dark maroon color on the inner. Somewhere I have measurements taken from the original 454 plate that was given to me by the current owner. I have several pictures of the plate from about 10 years ago. I do not have his permission to share the photos, or his information.
I do have notes on the measurements and if I can find them I will share. I believe the diameter was around 12" and it reads EXACTLY:
BALDWIN LOCOMOTIVE WORKS
454
PHILADELPHIA.U.S.A.
Note the period, not a comma, after Philadelphia...
Casey