Is this 2B vs. N endgame won for the bishops? Tim Krabbe gives this position on his list of serious promotions to rook and bishop:

[FEN "8/8/5b2/8/K7/4N3/kp6/8 w - - 0 1"]
[White "Boniface"]
[Black "Pugh"]
[Site "Bristol"]
[Date "1995"]

1. Nd1 b1=B


And states that: "Although the position was then technically won for Black, he did not manage to win, and a draw was agreed at move 92."

Can black win the resulting 2 bishops vs knight ending, and if so can it be done within 50 moves to avoid a draw? I had Stockfish 5 grind at it for almost two hours and a depth of 83 but it couldn't find a win.
Try Syzygy tablebase: https://syzygy-tables.info/?fen=8/8/5b2/8/K7/8/k7/1b1N4_w_-_-_0_1



Please ignore DTZ if you don't know what it is, look at DTM. It's checkmate in 139 piles with perfect play.

No, the position is drawn under the FIDE 50-move rule.