I have just installed a set of rear Wilwood fixed calipers with 13 inch rotors from ToddTCE. This a very neat setup that requires a little work to do, but well worth it. Now my MM has Wilwoods on all corners.
This is a project that ToddTCE has been trying to get off the ground floor and I agreed to help him.
I think that Todd may have a kit available in the not too distant future.
There are more pics in my gallery.