The largest margin of victory recorded in a horse race was by Secretariat in the Belmont Stakes in 1973, where he won by 31 lengths.
UNC in 2009 with a 20.2 average margin of victory
The largest margin of victory was 30 pts in a champtionship game. Not sure about just tournament games.
The largest margin of victory in the men's final was in 1990 when UNLV beat Duke by 30, 103-73.