Take it to a 1/4-mile track and test shifting it at 4500, 5000, 5500 and 6000 RPM, then look at all the incremental numbers and decide what RPM worked the best scope
If it went fastest shifting at 6000 RPM try 6300, and then 6600 RPM, you need to find out what the car likes for the best results wrench up

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)