Has an NBA game ever ended 91-77?
It has. 91-77 has been a NBA final 21 times in 73,172 games. The first was Minneapolis Lakers beat Syracuse Nationals on April 14, 1950; the latest was Cleveland Cavaliers beat Houston Rockets on January 15, 2016.
That makes 91-77 the 952nd most common final score out of 3,189 that have ever occurred in NBA. One point away, 92-77 has happened 32 times and 91-78 has happened 27 times.