Good luck! If you find one be prepared to pay topre prices ;-)
1. Buy a black Filco Linear R and a white Filco Tenkeyless
2. Swap out the casing and keycaps
3. White Filco Linear R and a black Filco TKL
4. Profit?
p/s: Owai, it will still cost over Topre's price... Sell the black swapped keyboard(with no warranty for sure) to get back around 80-100bucks back.