There's threads around here that talk about adjusting the kickdown cable. It's supposed to be done with gauges by experts but there are jury rigging type threads around. If you are happy with the shifting its probably ok.
Threads here talk about not going wide open throttle and allowing the car to shift into overdrive. The overdrive band is weak. So to preserve your tranny go wot in Drive not overdrive.
For me, I'd want the tranny to kick down for good highway passing. That'd be my driveability test.
1992 Tbird LX 5.0, 3.73 gears, 1995 Cobra intake, deleted air silencer, 2.5" mandrel bent dual exhaust, SCP shorty headers. Updated four-hole fuel injectors. SK shift kit in AOD. Vogtland 0.9" springs, Tokico and Bilstein shocks.