Hello capt_akun,
A good source for some up to dat information would be Wayne Crosby from WAAC. He is chief ground school and deals with jaa-stuff daily. I just finished my self study jaa ATPL's ( 14 subjects) in 5 months ( I couldn't do it faster cause i had to do the groundschool). It has cost me about 8k all up (exam fees, books, accomodation, airfares,...)
There is recognition of prior learning, so you won't have to do the groundschool.
But it is still a big effort, and is rather expensive. You might have to check the LASORS, in which they explain what experience you need to convert your liscence without redoing any of the theorie I think there is an air law exam anyway).
I would give |Wayne a call, he does seem to be very well informed.
Send me a message if you would like his phone number. Or check out
WA Aviation College
Greets and good luck,
Peter