I added a Shelby Fuel level gage right next to the Fuel Pressure Gage. So I have four gages on the top row, not what they came with but I like it.
You have a Centroid sender in the fuel cell. Go to
http://www.centroidproducts.com/fsafe.pdf to find out how to adjust the sender with full or empty tank settings. It's pretty easy to do, but the fuel level is never accurate nor linear. It starts moving off of Full when it's really half a tank. Could never get it to move uniformly due to the fact that the sensor is bent in the cell. Anyway, better than counting mileage.