That's a fun size rod. I've got a Hardy 6' 3 weight glass rod that I've got overloaded with a 4 wt. It's probably my favorite rod to play with, and it casts 40 feet of line as nice as it does 10 inches of line. If you want to roll cast, a double taper line works better than a WF. Overloading will help you throw heavier flies, but a size 6 bead head with a 6' rod is a lot to ask of a it. You can go up to a 3wt, but I wouldn't go much heavier than that.