20+ years of "Building 904/727 for drag racing use"

You want to focus on getting the 2nd gear band off before the 3rd gear clutch pack comes on. This has a lot to do with 2nd gear apply lever ratio, 2nd gear apply servo and spring(s) and the number of high gear piston return springs.

On the flip side of overlap is shift flare, which is less common, but happens when the 2nd gear band comes off too soon well before the 3rd gear clutch is applied.