Dave,
I've been waiting for some one to respond to your questions. Since that hasn't occurred, I'll give it a shot but I'm reluctant to respond without any 1927 documentation that gives direct answers to your questions. Some 1928 information gives response to your questions but they make you question the meaning.
The 1927 Chevrolet Duco Specifications listed in the 1927 Chevrolet Service News make no mention of the colors in the door opening areas. However, the simular 1928 information for the Coupe body uses the phrase "Door Openings Facings and Scuff Plates" were painted body color.
On the question of color for the firewall, the "1928 Chevrolet Striping and Color Guide" uses the term "Front of Dash" and states that the Closed vehicles ( Coach, Sedan, and Coupe) were painted Black while the Open Vehicles (Roadster and Touring) were painted Body Color. Since this Guide refers to the instrument panel specifically, listing the various body colors as the Body color for that model, I take the term "Front of Dash" to mean (in your terms) the firewall. There are other areas in various Chevrolet information where the term "Front of Dash" is use that specifically looks at the "Firewall". (*In todays world, an automobile manufacture employee using the term "Firewall" might well be looking for a new job. It's a term the lawyers say they can't defend.)
Last edited by Oldie; 12/16/16 05:36 PM.