Marty,
I worked for Chevrolet dealers as a line technician from 1971 to 1992. As far as I can remember, I never saw a painted solenoid on an original 1967-1969 Camaro starter. When rebuilding starters, the parts departments always supplied me Delco-Remy solenoids and they were always plated and had the Delco-Remy logo in the center of the end cap. Hope this helps.
boston14