Best 7.5 brakes in order
Cradock brake disks (only need 2 to endo your buggy) you can get them from www.ratzas.net
and they are cheap to
Ferdo or kyosho heat stable, these are also great but more expensive.
Stock k2 brakes
Almost all the pro's that run a kyosho or ofna use the cradock brake discs. You install one front and one rear and you remove the brake pad material and run the metal against the disks. They last forever and if you spill fuel on them they don't fade.