I have for sale a 919 rear caliper in gold. Has all hardware except for pad pressure plate but you can reuse yours. Caliper bracket is not included.
As you can see, it cleaned up super nice. I also brought the piston out a little for cleaning and to inspect it. The piston is visually perfect and operates very smoothly. At most, you might want to put a seal kit in it but, then again, it's most likely fine without it.
I traded Paul my black rear caliper for his gold so I no longer need this one.
$25.00 plus shipping and PayPal is fine. I put it in a very small box to keep shipping cost down.