Shimon is indeed a beautiful cat!
I looked up Siberian cat in a couple of my cat books, and it is listed as Siberian Forest Cat. It is also grouped in with the Norweigen Forest Cat and the Maine Coon Cat.
All three cats look a lot alike, and have very similar personalities. They are also considered a 'natural' purebred, so they can have any color and/or markings.
I wonder if N. Forest cats would be okay for people with allergies, since they are soo much alike?

Anyway, what a great looking cat, and the web page was wonderful!