Don't know if you did this, but right between the band adj. and the other band strut is the accumulator. Remove it and make a rod to replace the spring. Make sure it fits just right. The accumulators job is to soften shifts and by blocking it off will improve shifting. And there's a easier way to correct the geometry. Remove everything off of the side of the carb. lever and make a templet of it. Than remove the arm off the trans. and make a templet of that. Cut/drill the pivot points on both and set them on your bench. Then measure the full throttle of the carb with the choke open (where the cable goes) and then measure full travel on the kickdown lever on the trans. Now you can set it up flat on your bench then with a ruler mark the full sweep of both the trans. lever and the carb opening then put your cable on the templets and see what you got. It sounds like a lot of trouble but it's a lot easier than what you have been going thru. Also I've seen others recommend a manual shift valve body. They work great and after a day of 2 of driving it you got it. My wife even drives them with no issues. You can teach your wife or not depending if you want her to drive it, lol. But seriously all my kids also drive mine.
You need the Lokar throttle cable and kickdown cable kits. They work in unison. Anything else, you'll be playing this guessing game forever. Better yet, procure the correct linkage(s) for the engine/transmission. The stock parts work better if you have the right parts.
The nuts that hold the end(s) of the cable sleeve to the bracket(s) do nothing to adjust cable slack/travel/tightness. The only adjustment is where you have been doing it, on the length of the cable itself.
As long as it has the bracket that mounts to the rear carb stud, that holds both cables, it'll be O.K.
