Mystery custom made bass.... any clue?

[ksdaddy]

I recently picked up a mystery bass on ebay. The seller admitted he had gotten it from Goodwill in LA. There are no markings except for June 13, 1981 rubber stamped inside the pickup cavity and what appears to be 300 impressed upside down on the back of the headstock. It's maple and walnut with an ebony board and clearly very well made. It's not factory made in my opinion. It has a Badass II bridge and Grover tuners. I haven't determined what it had for a pickup; it's slightly smaller than a regular guitar humbucker. This bass had to have been gigged with hardcore; it's beat all to smithereens on the lower edges and the body is actually cracked across the control cavity. The arrowhead cutout in the headstock is reminiscent of some instruments made by Bernie Rico Jr. If anyone has a clue as to who made it, please let me know.

[ksdaddy]

It's not apparent in the photos but the wings are flamed maple on the front and birdseye maple on the back. The wings are laminated maple/walnut like the rest of the bass.