I stay around the 70 C with a max of 75 C. I use this temp with all of my motors.
GM says that the best temp is about 80 C. I don't think that's a good for most motors. The most motors can't handle to high temps and they forget that you measure the outside temp and that the inside temp is even hotter.
I have seen and heard that many motors are burnt because of to high temps.
So keep the motor cool.
Use a motor cooler as you are getting close to the 80 C.
Better a bit slower over the race than a burnt motor no finish and no motor after the race.