Biggles,
Just been through the process. You can add any new rating/type rating/aircraft category/design feature from either side. I have converted CPL & MECIR now and will add FIR in a few weeks. You can not however use the TTMRA to keep things current.
Any aircraft type ratings from NZ will add design endorsements in Oz, depending on the aircraft type. CASA have a list of aircraft and any extra design features. I had a c172 added and ended up with Manual pitch prop control (Piston) as somewhere a c172 exists with manual prop pitch control.
Hope that helps. Have you written the stat dec yet? PM if you need any help.
good luck.