As I said previously, the problem the Australians buying the Virginia class would be getting the purchase through either, let alone both, House iof Congress. Even if they could it would take years - and they would also go to the end of the line behind the USN requirement.
Technology transfer is something the various committees would fight long and hard over.
The U.K., however, already has the technology, transferred aver the last few years for the PWR3 reactor*, which will fit comfortably inside an Astute.
All the UK required was for the President to authorise the UK to share what they already have - which he has done.
*
https://en.wikipedia.org/wiki/Rolls-Royce_PWR#PWR3
I workday think the main questions would be whether they get either of the last two boats with the PWR2b, for which, from what I have read, the line has been closed. I would doubt it.
The question would then be whether any of the Oz boats would be built at Barrow with a line then opened in Oz, or whether jigs and associated equipment would be transferred to Oz once boat 7 gets past the stage they are required.
In either case I would assume the reactors would all be built in the UK.