Camaro 67 chassis color

Hello everybody!

I have a question that I have not been able to find out how to solve even the thousand pics available on the web.

I need to know how to paint the underside of a 1967 Camaro, I want to replicate the correct factory stock scheme.

I know that most of the American cars of that era were painted on gray primer and then with a body color overspray at the sides but I’m not sure if this applies to the Camaro because most of the pictures I have seen show the chassis entirely black (chassis frame and everything) do somebody has specific information on this topic?

Thank you in advance