69 Cuda factory disc brakes

I leave the calipers on the car and pump the pistons out hydraulically.That's the best way. You may have to restrain the unseized ones with C-clamps to get the seized one to move. Do one side until all 4 are nearly out,restrain them, and move to the other side.
I highly recommend braided,teflon-lined front hoses. Very big improvement in brake feel.
I also can't say enough good things about Silicon brake fluid. In 17 years none of my KH pistons has ever stuck again. This was a common issue back in the day.

And they are great stoppers.