Has a FIBA World Cup game ever ended 66-58?
Exactly once. On October 30, 1954, Paraguay beat Peru 66-58, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 66-58 in league history.
That makes 66-58 the 240th most common final score out of 863 that have ever occurred in FIBA World Cup. One point away, 67-58 has happened never and 66-59 has happened 1 times.