Questions: Headlights and Seat Heights.

So as I've mentioned in previous posts I've just purchased a 1973 Plymouth Duster just like the one I had in my 20s. It's at the body shop getting a fresh paint job right now so I've been reading everything I can (bought the service manuals for it) and have been buying parts for things I want to fix or replace. Since I don't have my car right now I can't check certain things and was wondering if you guys could maybe answer a few small questions. I have tried searching Google and the forum but didn't see anything.

My first one is about head light bezels. With my new paint job in the works I decided I should polish my bumpers when I get the car back so I did some research and bought some products and then I started thinking about polishing the head light bezels because they're that oxidized matte gray color. Does anyone know what metal type those are made of? Is it aluminum or sheet metal? Tin? Will they shine up at all with the right tools and product?

The second question I have is about seat height. If I remember correctly the seat is raised by basically adding spacers between the floor and the seat mount and lowered by removing them. I haven't looked under my seats to see if there are spacers but I'm 5' 10" and even with the seat all the way back my head hits the ceiling on every bump in the road. I don't remember that being the case with my old duster and the guy I bought this one from replaced the seats himself and was pretty short (not trying to shame just adding context) so my question is do any of you hit your head on the ceiling, if so how tall are you and what are the odds he raised the seat to better accommodate his height? Or used the wrong seats?

Do I have any options if there are no spacers to remove?