Help with ball joint and steering linkage

[JimboC10]

I have a 68 with front discs. I do not know what spindles and ball joints were used for conversion. I supplied 1975 upper ball joints and CPP lower control arms for 1973-1987. My local shop did the work. When I got truck back I see the nuts are so far down that the cotter pin hole is no where near the castle nut. The nut can back off now with no cotter pin to stop it. See pic.

Also they told me the steering center link was on backwards and they flipped it around. I have since researched this and it appears they were wrong. See pic.

Any ideas on what ball joints I should use and steering linkage setup?

Jim