I've got a pretty unique setup. JSK rears (like AZC), but the fronts I got off of Austin (240zhoke). They are a custom aluminum hub with a 12.2 x .83 vented rotor. He was using a Buick GN front caliper (popular with the roundy round crowd), I figured out that a Wilwood caliper fit perfectly. The rotor AND hub weighs 13.X lbs. I'm not sure that the smaller rotors will hold up for track work, but should be more than enough for autox. I also have the JSK front setup with stock hub and 12.2 x 1.25 rotors if I need for the track. If I recall the stock iron hub weighs 13 lbs and the rotor weighs 12. For comparison sake, I believe the iron Cobra rotor weighs 25 lbs all by itself, but you can get an aluminum hat and iron rotor setup that cuts some weight off of those too.
EDIT--Brakes and their use really isn't a function of the motor you have, so this post should really be in the BWSC forum. It's a lot more dependent on the tires. If you have 10" slicks and an L24 you can put a LOT more heat in the brakes than you can with a supercharged LS7 on 195/60/14 street tires.