Has a FIBA World Cup game ever ended 90-80?
Exactly once. On August 30, 2014, Slovenia beat Australia 90-80, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 90-80 in league history.
That makes 90-80 the 240th most common final score out of 863 that have ever occurred in FIBA World Cup. One point away, 91-80 has happened 2 times and 90-81 has happened 3 times.