Has a FIBA World Cup game ever ended 68-51?
Exactly once. On July 30, 1998, Argentina beat Nigeria 68-51, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 68-51 in league history.
That makes 68-51 the 240th most common final score out of 863 that have ever occurred in FIBA World Cup. One point away, 69-51 has happened never and 68-52 has happened never.