727 shifting in drag race??

It sounds like your kickdown linkage needs adjusting correctly. Keep this in mind. You can certainlt shift manually, however, that does not help the throttle pressure at all if the kickdown linkage is not adjusted correctly, so essentially, all you are doing is taking a chance with transmission failure. Without the kickdown right, the throttle pressure is still low and not holding the clutches together very well and you are shifting at over 5k. Not a good scenario.