i must say, the level of discipline and road respect that the members have are quite impressive. One thing to remember though is to keep at your own pace and cars ability.
Closest to the west side will be Mt Macedon, but its still a far drive
Otherwise Great Ocean Road is the other option, even though its not really a mountain, the twisties are fun
Ive done the black spur / healesville / kinglake runs a few times as well, takes a whole day.