69 C20 Disc brake conversion issues

[rpmerf]

There is a major difference between the left and right. I would be looking into that. Given that both inner tie rods are the same length, and both outer tie rods are the same length, your center link is heavily bias towards the drivers side. You say the steering box is in the middle of it's travel. I believe something is not lined up right.

Is it possible the pitman arm isn't aligned correctly on the steering box, or the center link is in backwards?

I'm wondering if you have a bad pitman arm. I know it sounds crazy but I got one for my 97 suburban. Put it in and my steering wheel was 45* off. Googled around, it was a common problem, company had a bad casting that was a tooth or 2 off.

EDIT:
Wondering, if you pull the pass side in, can you get it to ~ 0 toe?