1965 Dart GT: help on diagnosis?

The kick down rod snaps onto a ball on a short lever on the back of the throttle linkage close to the firewall. The other end of the rod is a short right angle that fits into a bell crank on the transmission and is secured with a cotter key. Do you have the throttle linkage with the step down rod missing?
Do you have a floor shift console? A cable runs from that to the transmission, and you adjust it at the transmission for calibration of the shift functions, park, reverse, 1,2. We can give you more details. I love your project work with your dad. Keep it up.