Has a FIBA World Cup game ever ended 85-51?
Exactly once. On November 26, 2017, Chad beat Guinea 85-51, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 85-51 in league history.
That makes 85-51 the 475th most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 86-51 has happened never and 85-52 has happened never.