If I remember correctly, unless if they've changed something, USYD is pretty strict about its ATAR cutoff. The only way to gain entry into a course with a higher ATAR requirement is through its access schemes, which may be difficult to apply for if you haven't already, since its a bit late. Have a look at this page. You can try to contact USYD student centre, but I doubt it'd help very much.
If you still really want to study engineering at USYD in the future, I would recommend applying for Bachelor of Science (which you definitely have the ATAR for), and keep up some decent marks to transfer after first year. This isn't a waste of a year at all, because you can do many of your core units for your engineering degree in your first year as a science student, for example, 12 credit points of maths, some physics, chemistry and/or comp sci units if they're relevant to the area of engineering you want to get into (or if you to just study the courses for personal benefit). As a science student, you're also able to take many of the first year engineering (ENGG) units too.