I always understood the service manuals to to say that your kickdown linkage should be pushed all the way back when your throttle was open all the way. I would disconnect the bar from the carb linkage, push the kickdown linkage all the way back, then push your carb linkage all the way open and see where it goes to on your kickdown bar. You will probably find that the stud on your carb linkage will require the slot on your bar to be longer. That should get you close to where you need to be.