I run a small Italian Greyhound rescue in Tulsa, and deal alot with the North Texas Italian Greyhound Club of America rescue. I'm not sure they are the dog you are looking for, as they're smaller.
Big greys are great if you are able to take a walk, or have a large enough yard for them to run in- and range from 55-85 lbs.
I would go to Petfinder.com. All reputable rescues use Petfinder. You can sort by your zip code, age, size, etc.
Also, if you work with a rescue that fosters dogs, you get a whole lot more information about the dog, good and bad- but a foster mother (or father) knows the dog much better than a shelter- what are they like in a home? Would they deal well with being an only dog- a good rescue person is looking both for the best fit for you, and for the dog, and will work with you to find that good fit.
Good luck. PM me if you would like help with your search.
maggie