Has a FIBA World Cup game ever ended 86-66?
Exactly once. On September 3, 2002, Turkey beat Angola 86-66, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 86-66 in league history.
That makes 86-66 the 475th most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 87-66 has happened never and 86-67 has happened 2 times.