Will the front brakes from a c6 z06 fit under 18x8.5 or 18x9 c5 z06 wheels? and is there also a kit to convert the rear brakes to c6 z06 rear brakes?

 

I'm pretty sure that they would, I don't know why they wouldn't. I know that they won't fit under 17" wheels though. I don't know about the rears though, most people don't bother with the rears because the cost and effort outweighs the benefits. Also, you will not have a parking brake if you change the rears.