Natepolean,
A 13' 7 wt Spey will play and land any steelhead on the planet, as safely and quickly as is humanly possible. And 8 wt would also be nice, and I have a couple. I don't use them much, partly because my 7 wts are lighter in action and feel, and because 95% of the steelhead I catch are not large. And even if they were, I'd probably stick with my CND 13' 4" 7 wt or the Sage 7136.
Steelhead are the most over-rated gamefish in the world, or at least on the internet. For all the reading about giant trophy steelhead, one might expect that they are all large and all perform like wahoo, giant trevally, or at least like tarpon. They aren't and they don't. Use a heavy enough leader tippet and you can land 20 pound steelhead on a single hand 5 wt. You're gonna' hook more fish under 10 pounds than over. For all those storied Kispiox steelhead of 20 and 30 pounds, something is driving the average weight of fish in the system down to 13 or 14.
Your 8 wt Redington Dually might be all the rod you need or want. I'm not sure how far that rod casts. Friends have the 6 and 7 wt Dually Spey rods (12' 6" & 13') and I find them too tippy. If you find yourself on the Buckley or Skeena, you'll probably be more comfortable with a rod and line that reaches out 70 or 80' with little effort.
Sg