Removing seized Kelsey Hayes pistons

See, the hydraulic grease method works great, doesn't it, if you don't have the official factory Miller Special Tools from back in the dinosaur days.
Now let me add to this posting if i could.
If there is rust pitting in the caliper bores, that's not a big deal at all on the Kelsey Hayes style of brakes.
The piston "seal" is at the top of the piston bore, and not on the piston itself, like on the Bendix, or BUDD, disc brakes that Ma Mopar also used.
When the seal is on the piston itself, then yes the piston goes up on down in the caliper bore, but not unlike the Kelsey Hayes where the piston seal is "fixed" at the top of the bore and doesn't move around.
Kelsey Hayes had their s#%t together when they designed their brakes, not unlike the other two.
So what if the bore has some pitting to it.
It's not going to do anything.
Don't worry about it, loose any sleep over it.
What i do is get out my Dremel, with an 80 grit flap wheel on it, and lightly clean up the bores with that tool.
Works great, easy, peasy.
Guess if you don't have a Dremel, sandpaper, twisting around in the bores works, too.
But for me, my fingers don't twist, and manipulate, that well anymore, in my old age, so i use 'tools" to get the job done.
And one last thing, there is no such thing as an oversize piston on these disc brake systems.
Standard size(s) are what's produced.

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Thanks for this information. If you don't mind I'd like to get some clarification. Are you saying the piston and piston bore don't relate as far as sealing goes? The seal is all about the rubber?
I'm starting to get back on my 68 dart gt convertible and I'm rebuilding the KH calipers. The pistons are seized in the calipers so I'm soaking them in my electrolysis rust removal tank. I have the rebuild kits but figured I'd need new pistons once I get them out. According to your post maybe I'll be fine with the originals???
Thanks again.