We fly into Shanghai stay 3 days then leave via cruise ship. Do we qualify for 144 hour visa free?

You are eligible in principle, but you should have in mind two "little" conditions:

- You have to fly to SH on a flight that does not have any additional landing in mainland China beside SH and it should not have a landing in the country where you will be going after your departure by cruise from SH.
- Your cruise should not have a mainland China port call immediately after you leave SH.

To conclude, if your itinerary looks like: Sydney - Shanghai - Busan (South Korea) this is fine.