wwall: It is still a mate in three with 51.Nh6+, not a mate in 2. 51.Nh6+ Qg7 52.Rxg7+ Kxh6 53.g5 mate or 52...Kh8 53.Nf7 mate.
After 34.Bf7, instead of 34...f5, perhaps 34...c4 35.Bxh5 c3 36.bxc3 Qxc3 is best for Black and perhaps winning.
36...Qg3 doesn't seem to help. Better seems 36...Qf4. So if 37.Nf7+ Kg8 38.Nxd8, then 38...Qxh4 and 39...Qxe1.
After 36...Qg3, Capa played 37.Nf3. Why not 37.Nf7+, and if 37...Kg8 38.Re3 Qxh4+ 39.Rh3 and 40.Nxd8 should win.
Now Black wastes a tempo with 37...Qd6. Better seems 37...g6, trapping the bishop.
After 38.Ne5, White threatens a family fork with 39.Nf7+. Black played 38...Qf6, but any king moves looks better. Black is still OK if White tries 39.Nf7+? Kg8.
39...Rd2 looks weak. Perhaps 39...g6 and if 40.Nxg6+, then 40...Kh7.
Capa played 40.Bxc5, but 40.Nf7+ looks stronger after 40...Kh7 (40...Kg8?? 41.Re8+ Kh7 42.Rh8 mate) 41.Ng5+ Kh6 42.Be8 (42.Re6? Kxh5 43.Rxf6 gxf6), threatening 43.Re6.
40...Rc2? looks like the losing move (40...Rxb2 would be worse). Black should still try 40...g6 and 41...Kg7. Now, after 40.Bd4! White has all kinds of threats on the queen and king.
41...Qa6? looks bad. Black should at least prevent Nf7+ with 41...Kh7, but White still wins with 42.Bg6+ Kg8 (any other king move and the knight checks and the queen falls) 43.Bf7+ Kh7 44.Rf1.