I dont think your std brakes are going to survive track days....
34 gtr rotors wont go under z calipers
dont forget to put in decent brake fluid!
Just did my ceff in r32 gts calipers (same as z32) with slotted and cross drilled front rotors and 32 gtr rear cross drilled with ebc greenstudd and a r32 gts master cylinder stops many happy times,