You are very welcome. Yes that auction drum has a correct factory black painted interior. Complete with sloshed/brushed on glue for the interior paper tag.
Yes people did all sorts of strange things over the years with shelac and interior paint esp in the 70s. Open ended tom era. The fakes usually come into play on a higher end snare such as a clear coated Dyna. I doubt someone would go to much trouble, time/expense, to re paint a couple of hundred dollar eagle badge drum.
The white interior was found on a red/white duco interior. They might of sprayed the whole thing white primer first as a base coat inside and out. The clear coat and red was found on a Scotti Plaid. The black interior was like Rogers standard in the mid 1950s like we know the grey as late 1950s into the 60s. Grey changed over the years as well. First it was flat and then in the early 60s we have seen a number of gloss grey. Later 60s they had the speckled interior. Peace, Gary