I am using Wilwood six piston Superlights with 12.19 Rotors on my Jag front end Contemporary.I had to make my own mounting brackets and do a little grinding here and there but they do fit and yes I am using 15" wheels.
If you go the the Wilwood site they have all the caliper and rotor dementions so you can order what you need. Measure carefully.
http://www.wilwood.com/