Factory KH 4-Piston Calipers

You are dreaming to think you are going to find a functioning set of calipers that are not in service, and on a car right now. Anything that has been sitting as a 'core' will need a rebuild, and sleeves are the way to fix, and update an early design.
Your old cores may well be able to be rebuilt. C.O. surely has seen the worst for rebuilding. Let them tell it cant be done, not your guessing.