I used to work on the North Fork Clearwater... Kelly Creek and the Black Canyon don't exactly have great play, but they're fun mostly 3 to 4, with some wood. I would bring a creek boat for comfort and maneuverability to catch eddies above wood portages (road scout first). I never ran Irish Railroad, but it looks easily sneakable on the right with big water characteristics. I think there's something funky in the center that pins boaters. I wouldn't go into it too cavalier. The rest of the run is just big waves and not very interesting class II to III. There's probably decent play after the confluence of Kelly Creek and the Black Canyon.
Working at the fire outpost at Kelly Creek was the hardest summer I ever endured in my life!! We had an army ranger running our fire camp and we full on ran 8 to 10 miles a day, complete with pushups, pullups, and dips. After that summer, I could barely walk, but I was in the greatest cardiovascular shape of my life.
Stop in and see the secretary at the Kelly Creek compound! She's an old school boater that takes every chance to boat with the sparse kayakers that show up there. You would make her day! Can't remember her name, but they'll know who you're talking about...