I'm not saying I'm right or wrong, but I will throw some fuel on the fire:
A 1969 Camaro order sheet shows "bright engine accents" as included equipment on the SS (RPO Z27). Also, the "Camaro 1967-1969 Fact Book" by F. J. R. Incremona (copyright 1984), shows a few pictures of a supposed original '69 SS 350 and it looks to me to have a chrome air cleaner lid as well as the polished finned aluminum valve covers. According to Mr. Incremona, "Much time and effort has been spent in locating and photographing original cars."