Lachlan,
Thanks for your link to the Pacific intertie. I was not familiar with this but when living in Manitoba Canada in 1980's a very long HVDC( I think 1million volts) was built, connecting Nelson Rivers hydro sites to N Dakota.
All of the proposed lines go through desert or low scrub, which is easy to maintain fire-breaks and is of little hazard. No major fault lines.
It is beyond my expertise to model correlations between wind sites, but note that in UK its about R2=0.2. Australia's weather systems usually go West to East and take 2-6 days to travel so would expect a low correlation between West Coast, Tasmania and Eastern Australia.
Why I was proposing a NW link within WA is that power demand by industry especially LNG and iron ore is expected to become as large as the demand in the SWIS, and the NW region also has the best CST sites.
WA also has the highest costs of power because it uses so much NG, which would be better kept for peak demand. NG prices are also higher in WA than Eastern Australia, lower cost wind power would allow NG used in LNG compression to be saved for export.