Got'em, sort of...
Update on my search. Knurled bolts:
1. are NLA from BMW,
2. no one on this board had extras,
3. Karl Nelson didn't have them either,
4. nor did Peter at CoupeKing,
5. nor did Dan at coupeguy.
So... I paid Walloth & Nesch an arm & a leg for a set plus loan...