Hi Norm, I am also descended from James Cameron and Catherine McEachern and would be happy to exchange notes with you. I have quite a bit on the family in Australia but little proven info on their background at Morvern.
James Cameron's father was also James Cameron who was a brother to the Ann Cameron on the British King. (Hence James Cameron's son was the nephew of Ann Cameron) It has also been suggested that he was also a brother to Hugh McEacherns' second wife, Mary Ann Campbell (nee Cameron). I would especially love to hear if you have anything further on this puzzle.