1968 A body 10" x 1-3/4" brake hardware?

Correct is neat and all, but there were a lot of changes that happened for a reason- many of the early 1 or two year only parts were replaced because they were improved.

Now, I don’t know for sure that was the reason for this particular hardware change, just a thought. Typically the design and function of the parts improve over the course of a design run, especially mechanical parts. NOS brakes are the absolute last thing you want unless you've got a museum piece.