Front rack "wobbly" on 78 KC

A worn rack should produce poor steering, and possibly tire wear across the entire tire, but I would not expect a problem on only one part of the tire.

I would look at other suspension components for wear, and check the wheel alignment.

Check the ball joints by jacking up one wheel under the lower suspension arm, then grab the wheel at the top and bottom and attempt to wiggle it. Noticible play means that the ball joints need replaced.

While you are there, try to rotate the wheel left to right to check the outer tie rod arm.

I'd also look at your strut rod bushings, although if they are worn I'd suspect wear on the inner part of the tire.