Ditto above on the factory pivot bolt not having a spherical stop. I just removed them from my 64 Valiant last night. They look more like AM's 34751 "poly" bolt, but with a step down for the inner metal shell.
Since the innards popped out easy with my shop press and the outer bushing shell was left wedged in the LCA, I was thinking how a poly bushing would be nice to just slide into the shell. Like others, my concern is that a poly bushing doesn't support the LCA axially, so the torsion bar could slide back if its little rear clip were to fail. Since nothing to grab hold of to press out the outer shell, I tediously folded it in with a cold chisel then peeled it out. Tonight I get to do that on the other LCA. I see that AM sells a tool to grab the outer shell, but $42 and not sure how well it works.