If you have SEAS, and with that ENTER, you're pretty much guaranteed to get in. I'd be surprised if you didn't get accepted.
Anyway don't change your preferences around if you think your score isn't high enough. Keep your preferences in order of what you want to do and where. If you're lucky then you can get accepted. My mate is 3 points off a deakin course but he's keeping it preference 1 just in case he gets accepted