I have a Lokar cable in my 64 Belvedere that never worked correctly on the up shifts. As reported here. the Lokar set up is some what inferior when compared to the Bouchillon one.
I had originally set up my cable to make sure that I had the trans lever fully back at wot. The problem was that the trans lever was now not forward enough when at idle.
In order to get the correct geometry. I had to modified the factory trans lever by drilling and moving inboard the location of the cable mounting ball stud about 3/4".
I also added a lever return spring.