The broken one looks as if it might be a good bet. Stourbridge.
https://www.ebay.co.uk/itm/Bass-Collection-SB301-by-SGC-Nanyo-Bass-Guitar-Active-Pickups-Faulty/163510003862?hash=item2611f4a896:g:vZEAAOSwdgxcTbNl
The alleged SB300 might not be? No such animal as an SB300, IIRC; and no pics of the back. Shrewsbury.
https://www.ebay.co.uk/itm/SGC-Nanyo-Bass-Collection-Superb-late-1990s-Bass-made-in-Japan-light-and-fast/173767951520?hash=item28756084a0:g:ECYAAOSwIbpcUFZv
I suspect that would be seen as fraudulent. It's not as though you could provide the goods in question, after all. So it would be high risk if you had any sort of reputation.
Do nylon-coated strings survive picks well? I'm thinking about trying this, but I'm not keen to write off a set of strings in the process. Anyone else tried? Thoughts on pick stiffness and material?
All Most thoughts gratefully received
Hm. I wonder how it compares to this?
https://www.ebay.co.uk/itm/aria-pro-ii-bass-Guitar-ZZB-deluxe/254049411117?hash=item3b2686602d:g:eREAAOSwNeVbgFup
... if any prospective buyer can get over the shape of the headstock, that is. Astounding.
https://www.ebay.co.uk/itm/Framus-Les-Paul-Bass-Bj-68-Vintage-selten-Hofner-Klira-Bassgitarre/362523232934?hash=item5468118aa6:g:JRIAAOSwpEdbXfFY
My guesses:
If it's just (!) a revision to the headstock and a new bridge, it'll probably be tunable. It might be really muddy though.
If seller has put on a new neck of a different length, and the body hasn't been revised to handle it... very unlikely.