Has a FIBA World Cup game ever ended 84-64?
It has. 84-64 has been a FIBA World Cup final 5 times in 2,041 games. The first was Russia beat Argentina on August 4, 1994; the latest was Tunisia beat Angola on September 16, 2018.
That makes 84-64 the 22nd most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 85-64 has happened 2 times and 84-65 has happened 3 times.