The current Epiphone Thunderbird case is a slightly different design. Trapezoid shaped.
One of my customers bought one last week for his BaCH Fenderbird.
But I do think the NR would still fit if you flip the interior like Carlo and I did.
The Bach 'Fenderbird' is about the same overall length as a modern Thunderbird, unlike the original JAE FenderBird (and my replica) which is a few inches shorter due to the compact body. My TBird style basses and I'm assuming the JAE original fit in a Fender Jazz sized case.
Because of that compactness they're less prone to neckdive than the 'lets just take a TBird body and stick a Fneder neck on it' basses.
I briefly had an Epi Explorer, and the case was noticeably smaller than the 2013 Gibson I'd had previously. As a case designer of 20 years, I just don't get some of the things I see out there...
The only off the shelf Explorer bass case currently on the market I know of is the Dean which leaves around five inches between the end of the headstock and the case. Ungodly huge.
That's why my EBirds are priced with a gig bag instead of a case. I've had three customers add the Dean case, the rest opt for the bag. One of the three immediately bought a bag after receiving his bass.