Why don't you use a Korean neck from a CH-12? A lot cheaper but still great necks. My CH-12 lost its neck to a new B12S -style body in 2008 and while I didn't think about the ergonomics at all (well, if I did I wouldn't play a 12-string bass) it's a much better bass now. It's a set neck, of course.
Of course the B12A neck has a different headstock but the bass itself (B12A) looks so great I'd be sad to see it taken apart. How about putting Thunderbird pickups into it?
Because if I'm going to make a USA made bass, in the USA, I want the neck to be made in the USA....But mainly the Quality and craftsmanship is second to none. I owned a Korean made Chap 12 once...for a few weeks. I didn't like it.
