Has a FIBA World Cup game ever ended 90-61?
Exactly once. On May 20, 1970, Cuba beat Australia 90-61, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 90-61 in league history.
That makes 90-61 the 240th most common final score out of 863 that have ever occurred in FIBA World Cup. One point away, 91-61 has happened 1 times and 90-62 has happened never.