From what George @ RDS told me, you can use DiscoveryII calipers; you'll need to buy new rotors and brakepads, of couse. I did this and it still stops just fine, even pulling a trailer, no warped calipers or fading. I did have to make new steel lines that run from the rubber hose to the calliper itself.
"Every normal man must be tempted, at times, to spit on his hands, hoist the
black flag and start slitting throats." - H. L. Mencken