I went and visited a friend who is working on a 1965 Impala convertible. The question is: what is the color of the firewall? I said that it is "semi-gloss black" or 60-70% gloss black, similar to the color of the underside of the car. Correct?
If that is correct, what year did Chevrolet quit painting the firewall's body color?

Now thats a good question. I am glad you asked that (as a speaker will say when he can not answer a question). My info. comes from cars pictured in road tests from the '60's.
So often they have under hood pictures and on the light colored cars its easy to see. From what I can find the in the pictures the 1963 was body color and 1964 and up black. Also may have depended on body plant....intresting

Early 63 was the transition to semi gloss black, it was a plant by plant change. I had only seen one 63 with a body color firewall that was a very early Atlanta station wagon I had owned some time ago. I have to look but I have something stating what VIN's the change happened and as I recall it was late October or early November
John