i dont recall him being over worried about my seats but they are very tall. i know he measured them in relation to the steering wheel and height off the floor etc but the measurement he was really hot on was the height of the seatbelt mounts, if they had been on the chassis rail rather than the roll bar they would have been too low.
may be worth speaking to adrian h as i think he had to make his headrests taller to pass so will know.
if you can wait until next week i can ask my tester what they look for. otherwise call vosa technical line they know exactly what they are on about.
when he measured the seats im pretty sure he went off the bottom (e.g the top of the bottom cushion) but he took so many measurements it was mind boggling to keep up. i also recall he had a weird and wonderful contraption he used that looked like it was made from a few twigs and a couple of door bells with a level and a protractor stuck to it