4 piston calipers question

I’m slowly going through the mechanicals on my survivor 67 barracuda I bought from the original owner. The car had sat in a barn for 30 years or so.
I’ve gone through the rear brakes and I’m about to get into the front disc brakes.

Are there any tips or tricks on inspecting these calipers to make sure they are good? I know replacements are hard to find so I’m going to do my best to save the originals and get them working again.
Author: Fireguyfire