Can you press LCA PST pivots shafts in too far?

Seems like if I back them out too much then I won’t be able to get the C clip on the torsion bar.

Highly unlikely. There’s at least good 1/4” or more extra space available between the torsion bar and the clip with the torsion bars installed completely into the LCA sockets.

And again, just press the pivot into the bushing until the shoulder is flush against the bushing. You shouldn’t have any issues if you install them that way.