An 8-weight is perfect for coho, which means it is what you need. Sure, you will occasionally hook up with a king, but it won't be often, and unless it's a real bruiser, your 8-weight will be up to the task. You could use a heavier rod to target kings, but you would probably wear out your shoulder from casting it before you got a king to eat a fly (at least anywhere upstream from tidewater).

As for wogs, I have never caught a fish on one, so I'm far from an authority, but I use LOTS of spun deer hair with marabou and krystal flash coming off the back.