I think you need the switch and 3 speed motor, maybe the lever that goes to the linkage under the cowl also, I'm not sure about that
I converted my old pump gas Duster (put a low deck six pack set up on the motor) to a 3 speed out of a B body and used those parts in it The stock one stuck out towards the carb to far to clear the six pack intake and carbs
That was when I lived in the Mojave Desert in SO CA so I really didn't them but I wanted it to be street legal so they went on that car, worked good too