I just came across your status update and replied there, but I'll repeat it here too (and I'll share the pic you posted there):
For what it's worth, this doesn't appear to be a factory fretless (RS940) but a defretted RS924. A 940 would have no fretlines, and only tiny dot inlays near the edge of the fingerboard where the fretlines would have been, rather than inbetween fretlines. Maybe this helps lower the boundaries to have this neck refretted instead . Being a lacquered fingerboard there will be some extra work involved to do a tidy and invisible job. These are fabulous basses, I really enjoyed mine a lot when I had it, so definitely worth the effort! It was prohibitively heavy though, and nowadays I favour a narrower nut width.