Righto, as far as i know...
There is no 'Band 6' in ext subjects, just band 4, but i get wot u mean.
Secondly, ur raw mark means absolutely nofin: its ur rank, so u can still get above 90 for ur HSC.
Wot mark should u be aiming for? Well, my teacher says that if u can get 2/3 of the paper...