jag,
I have Mike Bontoft's vented rotors on the Jag rear in my Cobra. If my memory serves, they are Porsche rotors. They came with caliper spacers so we had to split the Jag calipers and insert them to gain the extra width to accommodate the thicker vented rotors. The calipers use the stock Jag parking brake setup.
I have worn out sets of pads on the setup both on the track - many road course sessions - and 30K++ miles on the street without problems. I am also still using the differential Mike prepared.
I found the EBC Redstuff pads to be quite good for both kinds of use, giving good stopping and low wear and dust rates.
Mike supplied custom hats for the rotors. I think he may have machined the Porsche rotors a bit to adapt them. Perhaps the wishbones had to be clearanced too; it has been almost 15 years so you can forgive me for not having that bit of info available
Mike's now in England doing kart stuff - I think if you go to his web site you could contact him directly for more accurate details:
http://bontoftkartengines.com/contact
Tom