Are you asking for a paint code to paint a wheel or asking where to find the correct red plastic (non-paint) wheel? If it's the latter, my best advice would be to search for an NOS wheel. Even in that case, it may or may not match exactly to what was installed on the cars when new. I'd be looking for a wheel in an old FoMoCo box to give some assurance that it was an older piece. If you decide to search for an NOS wheel, let me know if you come across a 64.5 medium blue wheel!