I thought it would be shorter too, but it's about the same length
I covered about half the bell with some aluminum foil, made sure it was grounded and fired it up. No difference. Then I took a closer look at the gun. It sure looks like it's at an angle. I'll dig up a single and dual magnet and give it a try.
I don't see any signs of a rebuild. I also don't see any part#. I'm just going my the seller's word that it's really a 12KP4. All it says on the base is "CBS Palomar". On the other hand it is an aluminized 12" CRT.