rear springs you can get reset, i would sujest this before lowering blocks
legally in queensland you can lower your car 30% of its original height, so if you were to reset the springs you would have nothing to show that you have lowered you car

and

in queensland you cant change to an a15, but an a 12 and an a15 visually have next to no difference at all
so you would be sweet with that for the untrained eye of a copper