William is just gorgeous, and he shows some pretty clear lineage to Maine Coon or Norwegian Forest cats, though, without Registry Papers or a DNA test, he's properly a Domestic Long Hair.
Here's hoping that you stay with us, and post more pictures of William !
I agree with the above, although I myself would compare him with a MCO. Norwegians may be as big, but they have quite typical somewhat prolonged, triangular face. While MCO sooner the jaw in a quadrate.