I have used a few different colors by Tamiya and Testors, but I think there are standard Rustoleum and Krylon colors that would work too.
The finish really could be that shiny:
Not that this isn't "gloss" or "semi-gloss", it's polished. The best way to achieve this look on a model is to either leave the metallic paint unvarnished, the second best is to clearcoat it glossy. A metallic paint with a dull/matt clearcoat looks odd, like a speckled gray, because the metal flakes are no longer reflecting light properly. A metallic paint under a gloss clearcoat still looks a bit "off" under close inspection, but just fine when wargaming with small scale planes. I gloss coat all of my silver planes, because it's more important to protect the paint and decals from handling than to look perfect.
Note that nearly all WWII planes left in natural metal finish had areas painted in dull colors, to stop reflected light from blinding the pilot(s). On B-17s this was the area on the nose in front of the cockpit, and the top inward quarter circumference of the forward part of each engine nacelle, usually in ubiquitous US Army flat olive drab. These areas should obviously be in a flat finish – that was the whole point. I achieve this by brushing a dullcoat over these areas after I gloss-coat the entire plane.
- Ix
PS: I expect the insignia and IDs were also matt or maybe semi-gloss – however the paint looked when it dried. AFAIK the USAAF was not clear-coating its insignia and serial numbers. However, I doubt anyone will notice if you fail to brushcoat the insignia, lettering and numbering on your planes with matt varnish.