looking for a guide as to which colors or chrome was on this engine.

I don't think that engine had any chrome. Orange valve covers, orange intake, and black oil filler tube in front with black snorkel air cleaner pointing toward driver side.

...not sure of a reference specific to a '68 327/275 (other than Jerry's books), ...but I'll second what BdZee said...

I concur - No chrome on the '68 327.