Not sure if you have an angled bottom tank or not, but check that your unit can rotate the full amount. On my first car, I turned the arm about 30degrees so it would clear the baffling, but ended up not getting a good measure for how much fuel was really in the tank. The float bottomed out on the bottom of the tapered part, not the flat part. Ended up having to modify the float to get it to measure accurately.
Also be aware, the cork seal they supply is a known leak point. There's just enough pressure from the fuel head when you fill up that it leaks around the gasket. Found that MotoSeal is the only sealant that will not breakdown with exposure to gasoline. FYI