Yes the ever asked question of "what temp should my engine be?"

now I know the answer is "tune to performance not temp."

However, what is the temp that no matter what is too hot? With my current engine which is a JP Modified Mugen x12, what temperature should I stay below? Looking for more concrete info other than "if it sounds and feels good then it's good." basically after running a few passes at high speed and bringing the car in I get temps around 260F and wanna know if this is safe. I can richen up a bit to drop temps right?

Thanks for any replies.