is there any clubs in Sydney that will accept my mini and 80s falcon so I can switch them to historic rego?

Sure are,
Many car clubs on the scheme are non- exclusive with regard to make and model, provided they are 30+ years old.
eg. The Sprite Car Club has historic cars ranging from a Lamborghini Espada, 1947 Indian Chief motorcycle, to an Austin 7, and quite a bunch of Minis. As well as all the Sprites and Midgets.
And no, they don't have to be bog standard either.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

are you part of any club? I have heard most clubs are strict towards attending monthly meets and runs and so on

Only some clubs are.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

http://www.ocsc.net.au/

The old car social club takes any model car they have a annual show at the flower power moorebank every year and any make of car turns up

This years show is on 13/03/2016 Old Car Social Club Inc. 12th Annual Show & Shine
Flower Power. Newbridge Rd. Moorebank I went about 2 years ago and quite a few cars were there all makes