pretty much all ex500 racers would tell you they run either a 110/70 or 120/65 up front w/ a 150/60 rear.
Whether they run the 110 or 120 is purely a matter of personal preference until you're getting within 110% of top expert lap times. Then you'll find more people on the 120 beacuse of grip and feel issues at the extreme limits of traction...
But untill then it seriously doesn't matter, so if you've got a 110 on there, run what ya brung, that's what I've got on my race bike.