Seing as brake calipers are almost ridiculously easy to tear down and rebuild, I'd completely take the things apart, clean the hell out of 'em, bead blast 'em, clean 'em again and then PC and not worry about rubber parts cooking off. (just make sure you mask off/plug the cylinders and all the bolt holes.)
Doing the job half-a**ed will net you a half-a**ed looking job.
My $0.02
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