puppy breed shepherd mix

Hello all! We recently "adopted' a rescue pup, who was found on the streets here, and by my best guess, he is a mix of Shepherd/lab/ and maybe chow? He is approx 5-6 months old, 45-50 lbs, and has lost most of his puppy teeth...the woman who actually found him, had him for about 2 weeks before...

This is my baby Snow (because he resembles a snow leopard) I was wondering if anyone could help me guess what he is mixed with. I was told australian shepher but I am unsure because his tail looks more like a border collie or even a german shepherds. He is also getting pretty big (he's 4 1/2...