Yup, they´re copper plated beneath that "beautiful" salmon colour
Have stripped quite a few myself, which is easily done with paint stripping gel, as long as it hasn´t been fired yet.
Somewhat harder, if the paint has been burned on there on a used engine.
Here´s an example of the chimney, before and after stripping with Morse Paint Stripper:
(Attachment Link)
I like it better stripped.
Has anyone ever gotten an official answer as to why they paint over the plating? other than that is what Tom Jensen Jr likes? I know the majority of us prefer the "stripped" look...