It sounds like your fuel tap is not working and your float heights aren't setup right....as a minimum.

What's happened is that you're fuel tap let your whole tank of petrol draing through into your carbies. Your carbuerettors did not seal properly so your petrol then overflowed into your cylinders, leaked past your pistons and into your exhausts. I'm sure if you took your exhausts off and tipped them up, fuel would drain out.

Check/sort out those issues first, fresh plugs and fresh fuel and then see how you go from there. Where abouts in Aus are you from?