The rear upright/back plate is the same as a v5 sti-ra which has a 190mm parking brake and 290mm solid rotors. The weird thing is that instead of using a taller bracket like the "H6" brakes, the bracket is the same and the backing plate moves the mounting points farther out. So you'd need to change the backing plate, or if you got some 1st gen legacy turbo brakes you could use a 290x18mm rotor.
For the shortblock I had Ross Racing make some SVX pistons a couple years ago. They should be able to do another set pretty easily.
Also, I think you can use SVX rear axles to do a 5x114 hub swap into a wrx while keeping the r160.