My 2006 WRX donor is a DBW car and I am considering using an aftermarket ECU that does not support DBW (MegaSquirt 3). I will need to convert to a cable operated throttle body. I was wondering if anyone has experience with this?

Do you only need to swap the throttle body from an earlier WRX? Or is there more involved? Also are the 2.5L EJ255 throttle bodies a different diameter than the 2.0L EJ205's?