there are several options for you in Melbourne,
SAU is one of them
you also have the Nissan Datsun Sports owners club, www.ndsoc.com.au
and Classic Skylines Australia www.classicskylinesaustralia.com.au
i would have a look through those 3 and pick the one which best suits you.
the Skyline Nationals has been running since 2006 and every year its only gotten bigger and better i recommend everyone who can come does, at the moment with the early bird its a seriously cheap track day and with the professionals running the track day your guaranteed plenty of track time,
there are 12 Confirmed Group A & C Race cars in attendance including Most of the Nissan Works cars,
and the show and shine will easily have 200 cars in attendance, with trophy's for every Model up for grabs in both modified and standard class this event has always been about bringing people together