The key guard design doesn't look familiar to me as such, but the left pinkie cluster certainly does. I can't remember on what brand though...
About the only thing that I can say with certainty is that the case either came from a Kohlert, or was inspired heavily by Kohlert. So sorry, not much help here. Pete my friend, it's up to you..
I really don't have too much problem saying that this is a Buescher stencil. I know that Buescher had a ton of stencils and that they played around with the keyguards on a lot of them. Submitted for your approval, the Selmer USA Padless and Olds Ambassador. Of course, JBT's horn isn't exactly a True Tone stencil because it has single-side bell keys, but if you look at the Aristocrats, I think the keyguards are similar enough, right down to the "point" in the middle of the keyguard. The bell-to-body brace is also a match. I dunno if the horn is actually engraved "Elkhart," but that was a Buescher stencil name.
Of course, I'm only looking at one side of the horn. I've been wrong before .
FWIW, the (faux, I think) alligator case is actually pretty similar to the one for the ancient Buffet bass clarinet I used.