Here is a thought I'll throw out to those who are sharper on geometries than I am. In the circle track catalogs, there is a listing for an adjustable center link for GM [of course] applications. What they do is make the link with slotted holes where the tie rods, pittman arm, idler arm would go and they use an insert that fits into the slotted hole for the tapered studs with varying degrees of offset. They are doing this to lessen the bump steer. In the OLD! DC circle track books, they have a graph to help you decide which direction you need to go on adjustments to lessen the bump. What they show on the diagrams is to file the idler arm bracket to move the arm up or down and shimming the steering box to do the same. Years ago I met a guy who worked at King Richards, #43, shop and he told me one of the things they did back then was to heat up the ball joints arm and bend it as needed to get the desired results. Another thing I've pondered is, again for GM applications, having steering arms with different offsets. Of course you couldn't do it on the unitized ball and arm but what about the later units where they are a separate system?