Looks like to me it's just peacock front and back with some brown hackle wrapped in the middle of the fly tied with brown or rusty brown thread. I might add just a little dubbing to match my hackle in the middle underneath the hackle, It will help seat the hackle. I don't think it matters if the hook is 1x or 2x. I tie flies to try and match the size of the natural I'm trying to imitate. I could basically have the same size fly using a sz12 regular shank length hook as I could using a 1x sz 14 hook. I would be more concerned about the hook gap size. I wouldn't want my hackle to extend too far below the hook point.
"Have no fear of perfection - you'll never reach it."