Unless things have changed in recent years, there is no conversion from a CASA ATPL to a FAA one. The USA won't recognise the Australian licence, even though CASA will recognise theirs. The best you can get is a CPL. They also won't recognise any jet transport type ratings either.
To get the FAA ATPL you will need to do a course over there, sit the exams & pass the flight test. Any type ratings you want on the licence will have to be done again in full, at one of the training providers.
I really don't know why CASA doesn't cut them off & say no conversion of FAA licences until the FAA will recognise the CASA ones.