Every year your school has at LEAST 30% of students getting ATARs of over 99+, so you should be aiming to be in the top 30% of your grade OVERALL.
However it's not as simple when it comes to determining ranks in individual subjects due to scaling, cohort strength/teachers etc.
Don't forget that the cohort sizes you posted are for year 11 only. I would imagine quite a number of people would have dropped from each subject (except for advanced english). Also I'm pretty sure the average ATAR is 95/96 but the median ATAR is much higher (at least 97/98)
English: Generally you guys get around 90-100 band 6s so if you are in the top half you should be okay (assuming your rank in the external exams remain relatively similar). To be safe try to at least be ranked in the top 50 since english assessments can be very volatile (i.e. most tasks are marked as only whole numbers out of 15 or 20 except for trials which means a whole bunch of people will be clustered around the top marks.)
3U English: at least top 40.
2U/3U Maths: Generally your school gets around 60-70% band 6s in maths. Keep in mind that if 72 people picked up 4U maths then the 2U cohort size/competition will obviously decrease (i.e. there's a good chance that your year 12 2U rank will improve after year 11). Top 30 should be fine. 3U maths scales quite well and your school generally does quite decent so I would say aim for at least top 80 since you are also competing against the 4U kids.
Chemistry: at LEAST top 25
Physics: at LEAST top 15. Preferably top 10 since your science department isn't exactly the best... ]\
Economics: top 10.I'm pretty sure heaps of people dropped so the cohort is about 40 now. Your school doesn't tend to do as well in eco compared to english/maths so beware. However I heard that your head teacher is a senior HSC marker so if you are in his class USE HIM!!!!!
Remember this is a guide only. I'm just going off past statistics/hearsay. I tried to keep my estimates closer to the worse case scenario and don't forget cohort strengths can vary each year. Good luck