I still think you're going to have trouble. In Greys, an adoption group wouldn't DREAM of placing a high prey drive dog in a cat-home. Even though your kitty may live primarily outside, you must must must supervise your Siberians whenever they go outside. When excited and outside, your pups' prey drives will resurface.
Our group recently hosted a chain of lure coursing trials. One Greyhound owner let her dog run the course. However, when she brought her dog home, her dog proceeded to kill the family cat. This Greyhound had lived with the family cat for *years*, but when the Grey ran on the lure coursing field, her prey drive resurfaced, and the story unfortunately ends in death. I would highly recommend you reconsider acquiring Houston. You know, I sort of have the same situation as you. I could not stand Greyhound puppies for a minute. Contrary to their calm elders, Grey puppies are notoriously known for their landsharkiness. Therefore, I devote my life to show Pekingeses and adopting retired racers, who are years past puppyhood. Perhaps you could do the same :)