I agree with Barngirl. We've had greyhounds and a mixed breed dog with the same long slender head and thick muscular neck. We've used martingale collars on them exclusively -- although ours did not have any metal (the second loop is made out of the same material as the collar.) The added benefit is that, when correctly sized, they do not tighten on the neck too much but rather slide up under the ears -- this eases pressure on the trachea and does not cause the dog to choke or cough due to excessive pressure on the neck.
We now have an American Staffordshire Terrier/Shar-Pei mix (9-month-old) with a wide head but we still use the martingale type collar because the standard collar pulled too hard on her neck causing her to cough. Foster and Smith does carry these, so check them out!