It's a very aggressive board. I havn't ridden it but i've ridden similar and i dare say that for an intermediate, it will be difficult to progress with a t.rice. If you were going to go with the t.rice for oz i would go smaller than the 161.5 given your weight. The pointy tip on the 161.5 is a waste of space here.
I would suggest a 157 in the t rice and i dare say you could go smaller than that in oz depending on your boot size.
T.rice would be very stable but you might want something with a little more flex to allow you to progress.
Have a look at the TRS which is a little softer in a 157/154.
Anyone feel free to correct me if you think a 154 would be too small in Aus...but in a mervin board i don't think it is.