I did full hub conversion on mine, But the 32gtr caliper will fit gtst rotors no worries,
If you are getting an engieneer cirt, Then yes, You will need to match the brakes to the engine as if it were stock.
But like i said, Ive called the RTA or what ever you have were your from and its a realy stuff around, and will cost a coupel grand aswell, and need and emmisions test.
The few import mechanics ive spoken to, Told me to just come down and get a blue slip, ANd get a change of details form form rta to change the engine number over.
Sounds right though, Our gts4 also came in a turbo equivelent, You should be more then fine.
Ive put a rb26 in mine, But ive been told this is also fine as you can argue the cars usues the GTR drive train, Have used GTR brakes ect ect.
see how we go anyways