These are the approximate marks which would contribute equally to give an ATAR of 97 (percentiles in brackets):
English Adv: 90 (88)
Modern History: 91 (93)
Ancient History: 93 (95)
Maths X1: 87 (60)
Maths X2: 84 for an ATAR of 98 is the lowest the stats go (40 - for 84)
You can ask your teachers how many people beat these marks each year at your school and use this to work out your desired rank.