There's more than one adjustment but you have to take the pan off to get to the other one. The way I always adjust it is as follows.
Adjust the linkage so that the lever at the transmission is all the way BACK with the gas pedal on the floor. Then drive it and see how it is. If it holds the gear out too long, then adjust the linkage a little shorter and keep trying it. Also, it might be a good idea to make SURE the carburetor is WIDE OPEN with the gas pedal on the floor. If it's not, make that adjustment FIRST and then adjust the kickdown linkage as I described.