Well the stock lines won't work, but that was a long shot anyway.
The F3 Oro / 2013 F3 800 front brake lines might work. I did the same conversion on my F3 and went through two different hose suppliers before settling on the stock MV hoses mentioned above.
If you do investigate that, do check that they are the non-abs hoses. The F3 uses a nissin MC , not sure about your B4.
I made a thread of my conversion here on this forum, will check if I can find it.