I am fishing a somewhat unique situation here. The Delaware River system (West Branch and Main Stem primarily) require casts to rising fish of 60-70 feet with #16-20 dry flies. Any closer than 50-60 feet and you will never see the fish again.
youre likely going to be good with the expert distance for 60-70′ casts. A heavier taper would not load as well at extreme distances unless you downlined to a WF4.