[Boog]

Buck a couple pics of under the front end might help. As already mentioned the center link can be installed backwards and WILL cause "twitchy" symptoms even after a proper alignment. Do not depend on alignment techs to catch it as many of today's techs have never worked on a truck this old and even if they had they still might not catch it.
The 3/8" the sector is spaced over should not be a problem. Shorten the left side tie rods 3/8" and lengthen the right side tie rods 3/8" to even them out. You need to turn the wheels lock to lock to be sure the rims are not contacting the lower control arms. If they are it will limit the turn either way. The screech and scrub sound can likely be the wheel contacting the lca or the tie rod arm of the spindle. I run 8" rallys on mine and had to grind some off that point of the spindles.
We look forward to see what you find.