I think all the Bernunzio necks are for a 10 3/4” shell. The scale length won’t be perfect, but isn’t with the Harmony neck either. The Bernunzio necks are factory-made in China, not “to order” at all.
Since it's highly unlikely to be from a NO 3 5 string, it's a NO 3 plectrum or a Style M tenor — both used the same pot.
The tortoisoid interior binding and serial number tell us it is not a Vegaphone — besides being too early, those pots had black paint since the resonator was going to hide it. The lack of further embellishment tells us it's not fancier.