Kickdown issue

1972 Dart with 727. Linkages have been adjusted per the factory spec. With the pedal to the floor, the KD lever is all the way back against the stop but kickdown will not engage. This transmission was rebuilt at a local shop just before I installed it.

If the linkage is pushing the KD lever all the way back when the pedal is on the floor, what could be wrong in the transmission that it isn't working?