Thanks, friends.
I still need to install the propeller governor on the engine. I totally forgot to do that earlier but it is easily done after painting.
I did more and more research on the paint scheme and finally satisfied myself that the underside is aluminum lacquer on the original. I had many doubts but find several sources, including the IPMS Stockholm lists that I frequently study, that show a silver belly with Medium and Olive green upper surfaces. Opinions?