Good example for a end game where you may convert pawn to knight

I was playing black against a good opponent.

1. d4 d5 2. Nf3 e6 3. c4 c6 4. Nc3 Nf6 5. Bg5 Be7 6. e3 O-O 7. Bd3 h6 8. Bh4 Ne4 9. Bxe7 Qxe7 10. Nxe4 dxe4 11. Bxe4 Qb4+ 12. Qd2 Qxc4 13. b3 Qb5 14. Rc1 Qh5 15. Rc5 f5 16. O-O Qg6 17. Bd3 Na6 18. Ne5 Qe8 19. Bxa6 bxa6 20. Nxc6 Bb7 21. Rfc1 Bxc6 22. Rxc6 e5 23. d5 Rd8 24. d6 Rf6 25. Qd5+ Qe6 26. Qxe6+ Rxe6 27. Rd1 a5 28. Kf1 Rd7 29. Ke2 Kf7 30. Ra6 Rf6 31. f3 g5 32. Rd5 Ke6 33. Raxa5 Rxd6 34. Rxe5+ Kf7 35. Rxa7+ Kg6 36. Raa5 Rc6 37. Kd3 Rc1 38. e4 fxe4+ 39. fxe4 Rg1 40. Rf5 Rxg2 41. Rxf6+ Kxf6 42. e5+ Kf5 43. b4 Rxh2 44. a4 g4 45. Ke3 Rb2 46. Ra6 g3 47. Kf3 g2 48. Rf6+ Kg5 49. Rf8 g1=Q 50. Rg8+ {black resigns} 1-0

In the end game you can see that had I converted to Knight instead of queen, I could have prolonged and hoped for a better result.