One model that I have had on the building boards for awhile is the Miles M5 Sparrowhawk from the 1932 Kings cup Race in England. Like you I only have black and white photos and a description that the aircraft was "Creme" colored. It will be my best guess on what "Creme" color is.
The other comments were right, do not give the judges conflicting information, present information for one aircraft, and only one aircraft. Documenting the aircraft from this era is tricky.
One trick that Jack Sheeks told me, if the photo you present the judges had 3 details visible, then your model better have all three details. If you are missing one detail, do not include that photo in the documentation. Sounds odd, but from the judges point of view, if you prove that your model should have 3 details, and you only have 2 of the 3, the judge will lower your score.
Land softly,
Fred Cronenwett