It is not very common to have to replace the lower ball joints due to wear (the uppers are a completely different story!). Replacing the boot, boot retainer, and rivets is sufficient. Of course, this does not apply to buggered up ball joint threads or ball joint that are sloppy loose.
I was able to re-use my 148k mile lower ball joints and LCAs on my previous concours trailered 67 convertible. The ball joints were still tight!
Regards,
Pete Morgan