I highly caution anyone from doing the FAA ATP -> ATPL conversion.
Reasons;
1) Many airlines actively won't recruit you. Virgin, Jetstar, Qantas etc.
2) After converting not easy to go back and do the theory exams if you change your mind and need a local ATPL. Casa themselves told me not to do this as if you fail an exam you effectively lose your converted ATPL instantly.
3) With money spent on accomodation, flights, $$$ spent converting to FAA stuff and then back, its not beneficial cost wise.