Jumping in here and hoping I stay reasonably on topic.
The next step in my front end rebuild is... replacing the lower ball joint arms. I purchased Moog K781/K783 assemblies last fall after one of them finally came off back order. They definitely look beefier than the parts on the car now.
I also purchased some NOS TRW lower ball joint arms while waiting to see if the one missing Moog part was ever going to be available again. The TRW stuff looks basically like what's on the car now, and I have no idea how old it is. The instructions in one of the TRW boxes has a 1978 date on it.
Threads like this always throw me off since I was sure I was buying the "better" parts w/ new "Made in America"-labeled Moog. The boots on the old TRWs should be replaced, but otherwise they're just new old standard stuff. Now I'm second-guessing myself on which parts to install.
Oh, I'm pretty sure I read that there's something different about the Proforged lower ball joints' geometry than OEM. I'd like to be more explicit, but didn't keep my notes from when I was researching parts.
EDIT: I think we already installed the Moog lower ball joints and were only waiting on the correct tie rod ends to complete the reassembly. That's what happens when you don't wrench on the car when the cold weather sets in.