The SAU Vic Club has pretty full calendar (incl. cruises) so it'd have to fit in there.
Also unless we went the whole way, I'm not really sure how good the routes would be from on our half, the GOR only really gets good between Lorne to Apollo Bay, and simply doing the direct highway drive isn't exactly riveting (trust me I've done it a dozen times in the last few years).
There were rumours of a Oz wide "Skyline Muster" earlier in the year, but it didn't gain enough traction, damned shame as I would have gone for sure!
Edit: Could always hookup with some Western Vic people?
They seem to have a couple of events on the horizon: http://www.wvcruiseclub.com/forumdisplay.php?f=63
They seem fairly organised and mature, despite a high percentage of Falcadore drivers, and they have a disclaimer.