I`ve got your same set up George and I did mine like this:
1) Hold or affix the kickdown lever on the trans all the way forward.
2) Install 3/16 bit in bellcrank and kickdown linkage.
3) Remove all play from the rod traveling up from the trans pivot to the bellcrank and snap in place.
4) With throttle closed, remove all freeplay from the rod between the bellcrank and the carb.
If it shifts too soon then screw the linkage at the carb forward and this will increase the pressure at the trans. If it takes too long to shift then you have too much pressure and you`ll have to screw the linkage back. Only go a few threads at a time and test drive it between each run. When you get it right it should kickdown all the way to first from third at about 28 mph.
