I am no trans whiz by any means!! But I just had a 727 built and SMR told me for the kickdown to work it had to be a 71 and up valve body. The older valve bodies fit but won't downshift correctly. not sure if this helps but call SMR as they are GREAT to work with even if they have a Canadian accent!!

1969.5 A12 Bee EV2
1971 Charger RT
1973 Duster tubbed 500 low deck 10.90 monster
3 440 polara vert projects