You do know what the Mosrite BASS is, right? It's that 4-stringer (thank gawd Semie never had to deal with 5'ers, fretless, let alone ERB's...Mosrite ERB's... NO, it isn't right.
I'm an old-school fretted-four player and I can do PLENTY with that...)
But I digress, for those still here, the rest I assume are off playing those wimply little, what 10-12 gauge strings?

THE SWEET SPOT-
If anyone is still here- Why did Semie put the single pup ('65 Mosrite Bass; I have a Ranger which trust me, impresses me more each time I play it)
in that spot?
Looks? Super-Cool, the angle & such, set up against the neck, but more-
As a bassist who plays the right way- with fingers & thumb- That's another thing---you guitarists. with your-picks!



Note- for those Bassists who prefer a pick- sure, OK. I understand.
The positioning with the right hand is an important element of playing the bass and getting an appropriate tone and attack-
Putting the single pup where it is on the Mosrite single-pup bass is really nice- It allows you to play near the bridge or in the center- though it doesn't allow for playing over the pup, which alters tone and can add presence, not an issue
It is a great design element of this bass- The Fillmore Ranger; a great clone of the Ventures Model Bass guitar.
So interestingly to me at least is that element of Semie Moseley's Bass guitar- I don't know offhand of any other basses that have this placement- I recall some with an angle to the pick-up(s), but no others with the angle AND placement.
Just another Kudos to the Mosrite design, as if more were needed.