Hi all,
These people do a great job at reconditioning brake calipers:
http://www.brake-eng.com/
I have just had 2 calipers done by them. They are de-greased, shot-blasted, zinc dipped and pressure tested. New pistons, seals and dust covers. All for less than a rebuild kit. No brainer and no reason to get dirt under my nails nor burst into tears because you can't get the dust covers to stay on.
I've used their calipers before on modern cars and they are great value and good quality.
Luckily for me, I'm doing some work in their factory right now and got this done at a rate!