I know this is an old post but I don’t believe that neck is the original neck for this bass. JV serial numbers were from 82 to 84. And when Fender Japan first said they wanted to do a Medium Scale Bass, model PB-331, Fender told them they can only do it with the Squier decal on the headstock. It wasn’t until later in the 80s that you saw some medium scale p bases with the fender logo on the headstock.
I could be wrong but, what’s the date stamp on the neck?