The actual brake shoe should be the same across all Imprezas. I know that there is only one part number for the rally and gymkhana handbrake pads here in japan.
Also here is the thing. I am all about helping you guys out, but I am working two different brake upgrade options that are popular in Japan. The problem is the rotors are not available in the states. They came on non-USDM cars only. I will be speaking with WRXBRAKES about this.
These are the rotors and brackets that go with the kit. It uses the 322mm R34 rotor as far as I can tell. I believe that the rotor has the 5X100 holes drilled in it specifically so it will work on the Subaru since the GTR uses 5X114.3 I believe.