Has a FIBA World Cup game ever ended 99-83?
Exactly once. On July 13, 1986, Brazil beat Cuba 99-83, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 99-83 in league history.
That makes 99-83 the 240th most common final score out of 863 that have ever occurred in FIBA World Cup. One point away, 100-83 has happened 3 times and 99-84 has happened never.