ball joint spacers

Re: ball joint spacers (verboten)

In order to alleviate the more difficult bump steer issues I believe you also need to change the hieght of the mounting of the tie rod to the steering arm. Bump steer is caused more as a result of the angle of the tie rods and the angular change as the suspension moves through its range of motion.
The parts you have and intend to make are only part of the answer to correcting bump steer. They do bring the relationship of the lower a-arm back to a more normal angle relative to the body. Such that as the suspension goes through the new motion caused by lowering the a arm ball joint mount will be describing a flatter part of the arc, causing less change in the distance variation the tie rod sees. Since the variation is lessened the steering will go through a lesser toe in/toe out cycle (or what is commonly refered to as bump steer).
In order to further minimize the variation and change it is neccessary to also change the mounting hieght of the tie rod end relative to the steering knuckle mounting by an amount that either ensures that the tie rod follows the same angle that the a arm is at each suspension position. This may entail the tie rod being mounted to the opposite side of the knuckle (to the bottom for instance instead of the top surface).
Have you done a bump steer graph with your suspension to determine the geometry change over the whole range of motion (this is done without a spring installed and the body held in the correct relationship to the '0' position of the body relative to the suspension). This will allow you to create the correct parts to correct the suspension geometry faults.
They look like nice parts. Have you considered using a later model larger ball joint as the basis for this as you are introducing considerabley larger forces into the ball joint and lower a arm (what reinforcements are you looking at there?) ? You definitely might sell them with a considerable disclaimer as to their use and possible side effects.