Changing caster with shims?

[triumph406]

I have a 4x4 F350 CCLB, with a 4in Pro Comp lift

I've replaced the steering gear with a Red-Head rebuilt steering gear, which made a huge difference. But I still get a small amount of wandering which is easy to correct, however the truck doesn't like to self center after coming out of a curve, I need to turn the truck straight myself. Tie-rod joints are good, as are the ball joints.

I think it needs more caster, so does anybody know a really good alignment shop in Orange County So Cal?

Thanks for any help Dave