PH Bob:
While it looks like the five screws are evenly spaced around the mounting flange for the sender, they're not. As the gang from Sesame Street tells us, "One of these things is not like the others". One screw is slightly off, making the flange a 'one position and that's all' kind of affair.
At least on mine (stock 1969 VW tank) the float arm is off to the side (passenger side? - It's been a looong time), not to the front and that's the only way the sender flange will mate properly.
Good luck!