Has a FIBA World Cup game ever ended 54-51?
Exactly once. On January 17, 1959, Canada beat Mexico 54-51, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 54-51 in league history.
That makes 54-51 the 475th most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 55-51 has happened 1 times and 54-52 has happened never.