your 7wt will be pushing the limits, but 10-15 lbs should do - just no horsing around.
As our trout are limited here - we chase channel cats all over. General set-up is minimum 8wt (9wt is avg), and whatever line you have. Floating, ty. III sinking, or sink tip are the common (doesn't help I know). I've done a lot of research on Cats - although there are still arguements on what is their primary sense for food searching, due to the waters they inhabit - I tend to believe its their lateral line and sense of movement - then eyesight - then smell. All flies are as tied - no attractants / smells - but fill your boots if you must. Best fly is a DDH pattern drizzled up by a local. Catch the cats in their feeding troughs and have a blast.

darrell,