A note about wheel wire acid. I saw one a camaro caliper paint job web page that the dude used wheel wire acid to take ALL gunk off the calipers. I don't know how I feel about working with acid of that power, but I'm sure it would've very easily saved several hours of cleaning time. I have no idea where to get the stuff, but if you can get it and feel confident using it (wear goggles, gloves, and mouth protection) then I'd say to go for it. I would imagine you'd need to soak them in a tank or bucket of the stuff unless its a spray which to think of is even more dangerous.
Here's that thread with the camaro btw:
http://www.bfranker.badz28.com/fbody/calipers.htm