Howdy Jeff!
In our opinion, it is better to err on a wee bit too small than a wee bit to large when getting a tandem.
If you currently ride a mountain bike about that size it could be a decent fit, alhough you may need to fiddle around a bit with seatpost/stem.
Weight/color are not as much of an issue as proper fit. On the other hand, if you buy it and you're not happy with it, the resale in Australia for that bike should not be too bad.
If you need to resell it because of fit or whatever, you'd not loose much or any $$.
Just a thought and good luck!
Pedal on TWOgether!
Rudy and Kay/Zona tandem