Conversion
Hi Chairman
I believe that according to FAR's you need to meet the aeronautical experience requirements, meaning 250 hrs total time and the specific x-country time, etc...
Your Australian CPL will grant you a FAA PPL with ASEL rating, not sure about the AMEL. With this, provided you meet the aeronautical experience for the CPL, you can go directly for a checkride, knowing that you still need to be signed off by a CFI, meaning you will most likely have to do a few hours before getting that sign off.
Hope this helps.