Your jetting is a bit too lean. Jetting on the chassis dyno often is not the same as the jetting required when the car is moving at 100+MPH. (especially now that the fall air is cool and dense) Jet up to 72 pri and 84 sec for the track. Then come down a bit leaner towards 70 pri and 80sec jetting while watching the track 1/4 mile MPH from times lips. Max MPH indicate best power jetting.
70 to 73 pri and 80 to 85sec jetting is just right 99% of the time on a 750 HP carb on a N/A motor.