I agree with OntarioGreys. There are very very few intact Borzois and Salukis running around the United States, so I highly doubt the dog is a Zoi/Saluki mix. Plus, nearly all sighthounds possess that "arched" back, including Iggies and Whippies ;] The dog is most definitely part sighthound, but I would not say Zoi or Saluki. On the contrary, there are literally hundreds of thousands of Greyhounds, many of which come from racetracks, and, from time to time, an intact ex-racer does make it out. We're trying to prevent that more and more, but the inevitable does happen. Grey/BC mixes are also quite prevalent down in my area, so I can definitely see both breeds in King.
For those reasons, I'd say this dog is a Greyhound/Border Collie/Dane mix.