my first couple of track days earlier in the year were on nankang's...basically a really hard tyre that went off pretty quick.
it was still fun, and by no means scary. just because its the track doesnt mean you have to run super tyres. the crazy r32 micolour car
runs street tyres at the track and keeps up / beats cars running r comp tyres.
i'd just run on the tyres you have, if you have fun. go out and get some better rubber and go from there.
just remember to put heaps of air in the street tyres. i had like 40psi cold on the nankangs to stop the side wall going over.
if you have the cash then go the 595RS or ku36, well worth it. (running 595RS 235/45 all round now, love em)
marty (emts) in an s14 was running hankook fronts and nankang rears.
iirc the hankook were pretty soft road tyre (obvious not the same compound as ku/595), they wore like crazy at sandown. still had fun, i think...ha
he then run ku36 on the front last winton, was pretty happy. now has ku36 on the rear.