I am in a very similar position to you, never had 25 years away from flying but have had several very lengthy intervals between flights. It was a while ago now but I had FAA CPL CFI/I and my recollection is I did the CPL Air Law exam and then a couple of weeks of training to do a CASA CPL check ride. Got my CASA CPL and went back to the US and instructed for a while.
With thoughts of working in Australia I decided I needed the MECIR but the expense eventually defeated me.
I decided to do the road trip looking for work up north. At that time, about 8 years ago, there was a lot more talk on these pages about work up north. The prevailing wisdom was apparently to check into the youth hostel in Kununurra, or other town of choice, get employed at the bar or supermarket and wait indefinitely for a possible pilot job. I elected not to follow that course and after 12600km of driving only got close to a job once. I had 100+ hours of night flying but missed out on the job in Katherine as I did not have the Night VFR rating. It seems jobs are more plentiful now but hard to tell.
Anyway, I eventually ended up back in the US. I still think about flying in Australia but I baulk at the costs involved. Adding up the cost of:
* MECIR
* Dangerous goods certificate
* First Aid
* ATPL written
* First class medical
* ASIC card
and whatever else the employer might require I figure 4 to 6 months and $30,000+ versus just keep flying in the US. If I am wrong on those figures and requirements would welcome any comments.
Fud