Any good quality "rust-orange" shaker can from a paint store should be satisfactory to duplicate the original color. When neatly applied on a clean, polished alternator the look is like the original.
Another challenging restoration process is to get the correct stamped pattern on the side of the alternator. Some Mustang restoration shops might loan you a stamp.
Good luck on restoring a concours car.
Garden Grove, CA
"Everything that is really great and inspiring is created by the individual who can labor in freedom." Albert Einstein
65 Fastback GT. 65 Convertible. 84GT, 90 5.0 LX Convertible. MCA. Southern, CA