FINAL UPDATE:
I got the parts in from Rock Auto and swapped out both shackle pins and bushings. Both pins were worn, as were the bushings. There was some erosion in the leaf spring, but not enough to allow me to just push the bushing into place. Instead, I had to press them into place using the home made tool.
As to the Rock Auto parts, one bolt was fine. The other had threads that weren't quite right. Even the nut that came with the new bolt wouldn't thread onto it properly. I ended up using the old nut to chase the threads on the new bolt. This then allowed the new bolt to work as designed.
Thanks again to everyone for the help and advice!
