A 27.4mm post would indicate a very high end tubeset. Assuming it is Tange, like the BB shell and stays, it would be indicative of Prestige or Champion Pro. The frame seems slightly newer than 1982 via the presence of the two bottle boss ets and internal cabling. Besides the 1982 and 1983 Canadian Nishiki literature still shows things like derailleur cable routing over teh BB shell and chromed dropouts.

The fork is proably a replacement. A Tange steerer would typically have Tange stamped on it, along with an alpha-numeric date code. The bottom inside would also have six spiral ridges.

It's looks the frame is made entirely from standard Tange product and that makes me wonder if it's a contract frame manufactured by Tange. Things like dual bottle bosses and internal brake cable routing would typically put it into at least the mid-1980s. By that time most major manufacturers were embossing logos or identifiable designs on things like stays caps, lugs and fork crowns.

Of course, the fact that it's a stripped frame complicates matters, as it's always possible that some of the features were added. Regardless, in it's current state, it appears to be a mid-1980s, contract manufactured Prestige frame for a relatively small brand. Could be a local brand. Maybe there's a similar Aussie/Kiwi forum you could post this on?