You could pick up an old .22 Hornet and a sporterized .303 for a song these days, the nostalgia you get for free!

Seriously, there are any number of good rigs around today and very few bad ones. Sounds like a .223 or .243 would probably suit fine, perhaps trading up to a .30-cal magnum for that leopard when the time comes. Many of the lads here or over at AHN will be full of good advice no doubt. Magazines from the newsagent are another good source of ideas, the 'Australian Shooter' has a classified ad section for second-hand stuff.

My only advice would be to think long and hard before succumbing to the current 'super-short magnum' craze which might get pushed at you over the gun-shop counter.

Welcome back!