sbxx - I got your private message but I don't have enough forum posts to write back. I'll copy and paste part of my email below.
I was accepted as a non-standard into Griffith Dent. My GPA was 6.9, from what I can gather the lowest GPA cut off was 6.7. However, a friend that was accepted got in with an average GPA of 5 point something, but she had received First Class Honours in her honours year. There was also another accepted with First Class Honours, but I think her GPA was around 6 for her degree. I can only assume that First Class Honours is awarded a rank 99 by QTAC. You should check this with QTAC though.
I also put Griffith in #1 preference.
I hope this has helped, good luck!