He's a real cutie!! That's awesome that you're keeping him!!

I agree that a large mouse fuzzy should be good for him at that size. As long as you feed him whatever prey is about the same size as the widest/thickest part of his body, he should be happy. As far as care tips go, the main thing I've found is that they love to burrow, so if you can give him several inches of aspen, he'll enjoy that Kings have really fun attitudes, and are usually much more active than bps!