Yes I do think its encouraging that he spelled his name the same as Anthony, but I have to mention other possibilities that we have looked at. From the census you gave William of Abbeville would have been born 1880 or earlier. Is that right? Thomas and Joseph McMeen in Lancaster Co SC and Samuel McMin in Lincoln Co NC all had sons named William who would have been born close to this time. William was already married by 1790. Also notice that William of Abbeville named his oldest son Joseph, and we know that often the oldest son was named for the man's father. These are things I've considered. If you know what happened to any of these Williams please let me know.