Great idea! I have just been restoring a '46 6400 and was thinking about this too.
It will never be in a show, but creativity is more important to me. I think if you
take some careful dimensions for that radius surface and add a tad more for good measure, which can always be trim to fit you could make a pattern for putting on a
large piece of cardboard and that could be covered with whatever suits. I saw a guys old truck that had an old map basically wallpapered to the ceiling and it looked great. In fact, wall paper paste might be one way to go. Be creative.