Disconnect the kickdown linkage. Check to see if the carburetor is opening all the way with the accelerator floored. Once that is confirmed, use your hand to push the throttle all the way open (helps to remove the return spring). Push the kickdown linkage all the way back. Then see if the kickdown linkage hooks up with the rear of its slot against the carb linkage. If not, adjust it until it does. Once it does, you now have full throttle travel and full kickdown travel.
This is not the procedure in the shop manual, but it works just as well if you don't have a 3/8 inch drill bit handy. Also works for any kind of kickdown linkage, and they do vary.