1967 dart upper A arm bushing / bolt wear

Probably a combination of both.
But those adjuster bolts are pretty darn hard.
I haven't seen to many of them worn, in my rebuilding.
I'd bet on the bushing(s)
Since you already replace the ball joints, it's not that much more difficult in doing the bushings, also.
Then all your top end will be done.
Over and done with.