He is the kindest man I've ever known.and I have never seen (met is a better verb to use) asany good a man as helike him (OR: I have never met a man like him. OR: I have never met such a good man before.)
He is the kindest man I've ever known, and I have never seen any good man like him.
Yes, you can. But more idiomatic is something like this.
He is the kindest man I've ever known, and I have never seen anyone as good as him. He is the kindest man I've ever known, and I have never seen anyone as good.