One other suggestion: Get a piece of cardboard or paper that gives you 11" of length and enough width for the swing. Set your pivot point right at the middle (5.5"). Now without moving the sender, swing the float arm all the way up. Does it look like it will go to the top of the paper? And swing it all the way down, keeping the pivot point at 5.5". Does it look like it will rest near the bottom of the tank? If it doesn't, try to adjust your rod so that it will (think 5 7/8"). If you don't have enough rod, just go buy a common brazing rod and use it.
