Carl, I've seen some pics of a Sturmy interior, and I would say that the color leans much more toward white, with maybe a wash of raw umber to give it some tone? For discussion purposes only, I paste this photo:
Wouldn't you agree? Especially if you're going to put down any wash over it for definition--your buff is going to get dark. In the closed-up shadows of the model, especially in scale affect, you're going to perhaps wish that you went more toward white?
If you look at this link of the Munster Sturmy, and compare the interior with the exterior, I would say you'd be hard-pressed to argue that it isn't a more white color.
http://krimi.tripod.com/sturmtiger/sturmtiger005.jpg.html
I borrowed this one from the internet too--from "The Sixth Army GRoup"'s website: again, it's more white than buff....
Sorry to be a bummer, but hopefully you can get to it before you close it up and make it inaccessible?