Kelsey Hayes 4 piston calipers help

Just get a set of Raybestos rebuilt calipers from rock auto, and send the old ones in for core charge. Parts for these things cost more than the rebuilt calipers all assembled, bead blasted clean, and coated. Don’t forget to order the hardware kit; it is new stuff to hold pads in place.

Once you get the old caliper striped of pistons, you will still have to deal with pitted bores that will most likely need attention beyond honing.