Back on subject as to where in NSW you can run a good VMX these days?
Most punters love Buladelah. Apparently the facilities are going to be improved this year too.
The Lakes track gets a thumbs up from the post-74 crowd, without upsetting the pre-75 guys too much.
Historically, the Canberra club has been willing to modify their track to suit older bikes, and very willing to modify their track for National level events... I haven't seen it lately, but it has been toned down a lot from the dark days of 2009. Dunno if this would make it a suitable venue for the CMX Nats, but it could be an option to explore.
Most punters still rate the Coffs Nats highly. Again, its a modern track that can be modified to suit older bikes.
There's currently-operating grass-track venues in Gundagai, Cooma, and Bega (and Leeton and a couple of other places out that way, IIRC).
Finding a track isn't that hard - the real challenge is finding a track that is run by a friendly club/land owner
and finding a club that has the motivation to actually run the event.
More than any other factor, that's what will determine where any future Nationals are held.