I'm looking at the pictures of my australorp chicks and there are alot of similarities, except the combs on my chicks were lighter in color and mine had more white around the eyes. I can say though that your chickens will be all black in color.
I have two black sexlinks, the entire face looks different on your chick. Both the beak shape and comb are quite different. I would say from googling australorp chick you are correct.