Accuracy of aeromotive sending unit

I have the same set up. 1/2 tank is showing empty. I’m actually planning on dropping the tank back out. Somewhere I had found that the arm on the sending unit is adjustable and I’m thinking I can get it a bit more accurate.
http://www.tanksinc.com/pdf/Fuel_Level_Sender_Installation_Rev_1_5_15.pdf

The sender and tank are available from tanks inc and I believe aeromotive just installs their pump. My tank has tanks inc stamped into it.