dionb2014
From your long post I take back what I said. You certainly know better than I, the various issues affflicting the world economically & financially. Would you pleez forgive me. With your interest in this area, investment banking is certainly for you.
We all hear of the top investment bankers from Harvard Business School, Wharton & U of Columbia Business School (Warren Buffet still "teaches" there every year). Cambridge is great for science and of course in Economics as well.
I think you will end up with far better marks than you initially suggested - you'll easily get ATAR of over 99. - so no ploblem being considered by Oxbridge. Have you considered doing the International Baccalaureate programme (if your school offers it) instead of the NSW HSC? It's offered by, amongst others: Trinity Grammar, Ravenswood, Monte St Angelo, MLC Burwood, SCEGGS Redlands, Cranbrook, Newington College, St Pauls Grammar, Penrith.