Just my two cents but, I agree with giving the dog a bath as your best option. Having had both dogs and cats I can say wholeheartedly that, whatever smell a cat may have is insignificant compared to the smell of a dog. Litter boxes are a different story and really need to be kept clean, though.
One more thing that comes to mind. Try not to walk him in the rain. If you think he stinks now, you have a huge surprise in store if you ever get him wet.