Has a FIBA World Cup game ever ended 90-63?
Exactly once. On July 1, 2018, Croatia beat Romania 90-63, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 90-63 in league history.
That makes 90-63 the 475th most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 91-63 has happened never and 90-64 has happened never.