Per my Nov. 1969 printing Camaro Master Parts Catalogue the 350 & 302 shared the same valve covers in '67 & '68 (chrome it would appear from all pictures you can find). However, in 1969 the 350 shared the same (painted) covers as the other small blocks with the left one with an oil fill added to it. Only the 302 is listed with unique part numbers. My parent's '69 had a L48 and it was as the Camaro parts cataloque suggests. This was a station wagon so no one likely modified it in the one year the original owner had this car before my parents bought it. This suggests to me that any chrome valve covers were either added by the dealer, non-documented by GM or the documenation was never retained.
To add to the confusion (for myself at least) my (restored about 10 years ago by someone else) '69 L48 has chrome covers exactly like those in '68 but the left one has the revised oil fill which was added in '69 to the painted covers. My car was built near the end of the '69 production run. I am never the less changing back to painted units I found after a long long search.
As for air cleaners there are two 4BBL small block parts listed for 1969 with the second one apparently added later. Since there is only one air cleaner element part listed for non-cowl 350s physically they should be the same. Unfortunately, it doesn't say whether the new part was chrome. A check of other cataloques (Nova & Chevelle owners claim to have had the same chrome option for their SS equipped L48s) may help clarify. I may have no documented proof (other than numerous pictures) but I would say that any original chrome lids were most likely exactly the same as a non-chrome lid. I have yet to see a reproduction of either painted or chrome with the correct profile (bump on the top of the lid where the element sits).