The main thing to look for is heavy black down below the tips of the ears, which means he has decent mass, and cutters (prongs) a decent ways above the ear tips. Also, if the horns go out and around in somewhat of a heart shape it will really add to the length measurement compared to one that goes more upright. Most don't realize that the four mass (circumference) measurements on each horn are really what makes the score on an antelope.