No siberian is ever 100% cat safe. The dogs I have raised from puppyhood are no more trustworthy with a cat than the ones who showed up as 10 year olds.

I would strongly advise you never, ever leave them unsupervised together. My dogs have learned that if they want to be in the house, they have to leave the cats alone. I still won't leave them unattended. A dog inside is within my sight or confined somehow. I allow no interaction. The dogs can't chase, follow, or bug the cats in anyway. Even staring at them for too long will result in a quick trip to the door for the dog. My dogs have killed one of my cats, when she got outside. Single worst moment of my life was finding Dominique's body. The dogs had been fine with her in the house for five years, but when she was outside, in their territory, she was fair game, no different to them than a squirrel. They had no idea why I was so upset.

I do hope you find the perfect puppy for you and that you enjoy many happy years together!