I don't think you can get internal marks until the HSC is completed o: since every school is different, a 95/100 somewhere ranked 300+ would not be the same as a 90/100 in James Ruse. Internal marks only appear post-hsc as the total aggregate score needs to be compiled and then redistrubited...
You don't need to be first if the gap between 1st, 2nd, 3rd etc are relatively small. Like the last two posters have mentioned, SR's are less dependant on ranks the higher you are in terms of school ranking - as the relative gap between marks is lower compared to large fluctuations in higher...