Mike,
I can see what you're driving at, but it is my understanding that the CHS wants the locomotive representative of how it looked in 1937.
The plate wasn't cast until 1939, after the lines to Leadville were abandoned and after regular service stopped on almost all of the C&S 3' gauge.
Save the CB&Q frisbee number plate, but make one more appropriate for the 1937 era. According to the photos, the number plate on 71 was typical for the era and the type sported on the 9 at the target date. (see photo in Kindig, Haley & Poor of Curley Colligan and Pete Marinelli flanking the 9's plate on the last run).
The plate that 9 now sports was never used while she was in service, so why insist that the plate stays, knowing that it is wrong for the projected restoration date?
Rick