I have a 2 seater roof skin already, but looking at the roof on my 70 240z it's actually very straight, I don't see any obvious rust bubbles and it's not dented etc.. The sunroof isn't that large and so I'm considering repairing the existing roof because of how hard it is to find a good roof these days. My plan with the 2+2 roof is to use only a portion / section of it to repair mine.
If I make a mess of it then I'll just use the roof skin I have, if not I can sell the roof skin later.
I think the storage unit would make sense if you were living over there and able to send stuff to Australia. If I'm lucky with work I get to travel to San Francisco about once a year, often I've thought about finding S30z stuff while over there and sending it back but I'm never over there long enough to make it happen.
With the way the dollar is heading though I think the US is looking less attractive for S30z parts.