I was lucky enough to see my car come up for sale on the J-Spec mailing list at a bargain price, and from the previous experience of my partner importing a Silvia through J-Spec I had no reservations about contacting J-Spec straight away. Ben sent me approx. 80 photos of the car, kept in contact throughout the entire process and answered every question (no matter how silly it may have sounded), he really put my mind at ease. I was lucky enough to have J-Spec personally inspect and test drive the car for in Japan before I purchased it. They recommended a great compliancer once it landed and the whole process was made very easy. If there isn't a car on their mailing list that takes your fancy - tell them every minute detail (model, colour, options, etc.) and they will track down exactly what you need.
Speedo tampering is rife in the Australian market to the point where more imports than not sold by Australian dealers have had their mileage wound back. See how importing yourself easily avoids this pitfall.