I've done a couple of RAA -> PPL conversions, as instructor. The time and effort will depend primarily on how your RAA instructors treated flying - some are very professional and thorough, others seem to consider flying a hobby or game! Anyone should recognize your hours - where I would expect you to take some time would be getting up to standard with:
- Handling bigger/heavier machines - it might seem silly but, depending on what you've flown, even going from Jabiru to a C172 can take a little getting used to!
- Navigation - some RAA nav endorsements (or whatever it's called) are pretty arbitrary. A PPL permits you to fly pretty-much anywhere in the world, and I expect you to be able to navigate accordingly.
- Radio work, especially in control zones. This will depend on where you have flown, but if you're not reasonably familiar with control zones, everyone has some trouble with their initial radio work. I'd suggest you fly out of a class-C or -D airfield (e.g. Essendon or Moorabbin), to force you to do lots of real radio stuff.
- Theory - while the syllabus are similar to RAA, your PPL/CPL theory is expected to be rather more detailed and the coverage more thorough. The exams are CASA standard - not hard but you will need to know a wide range of subjects to a reasonable standard.
- General approach - attitude, thinking ahead, professionalism. Another thing that will vary depending on your previous experience. Some RAA sites treat flying like a hobby - even a PPL has the right to play with the big boys, and to put your family is a serious aircraft, so it's a more serious business all around.
I think just about anyone can upgrade RAA -> PPL but you might find it more involved than just acquiring the hours. All the best.