Help Me Calibrate My Fuel Gauge

I am in the process of trying to calibrate my fuel sending unit and fuel gauge on my 1970 Duster 340 Rallye dash. I checked the original fuel sender with my multimeter. It is in the correct range regarding Ohms.
I now want to calibrate the sender to my fuel gauge. I would like to make sure that "E" and "F" are where they should be.
Could somebody please help by describing or providing a schematic how I need to wire these up so that I can adjust the sender.
I have a variable voltage powers source. I disabled the mechanical voltage limiter and replaced it with a transistor voltage limiter. I am not an electrician so keep it simple if possible.
Author: fjrdoc