9wt hit the nail on the head. If you change a pattern by adding anything or taking away materials...or changing something...then you're no longer tying that particular pattern. You can call it whatever pleases you...or whatever you think it is...but don't give credit to the original tier since it could be an insult.
When i bought the book Flies for bass and panfish, i pretty much memorized it, cover to cover. I clearly remembered Waterman's Silver Outcast and that the author did not tie it with jungle cock. I'm also making the assumption that the author (Farrow Allen/Dick Stewart) tied the original pattern. You don't see many classic flies from the Everglades with jungle cock, either, since the capes are expensive and probably were not readily available. So that's why i made the assumption that the original Waterman's Silver OUtcast was not tied with jungle cock. Just an assumption, and nothing more.
Of course, you can call your flies whatever you want...but once you start naming names and giving credit, they should be tied "accurately". There's no question about it...every one of them can be "improved" or modified so it best fits our style of fishing. Some are changed for the better, and jungle cock certainly makes a prettier Striblue's Silver Outcast.