I'm admittedly ignorant of the specifics of the G-body suspension geometry, but solely geometrically speaking, if you change the upper - outer pickup point for the suspension the upright is going to travel through a different set of points. Hence in the case with the taller upper ball joint giving greater camber gain. Depending on the position of the steering pickup points (outer tie-rod) the effect on the "bumpsteer" characteristics will be different. As the top of the spindle is "pulled in" during bump so is the steering arm. Obviously less if the steering arm is very low, more if it is high. I'm even simplifying it to an almost 2D view with this explanation.
I'm just pointing out that to say that a taller balljoint has no effect on the steering characteristics may not be entirely true. Probably in most cases, it would be negligible, but still worth considering.
Maybe Marcus from SC&C will chime in - he knows this setup very well and can explain the differences of the tall ball joint to the AFX setup.
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