From a previous post on the subject....
I found another Tach which didn't specify the need for calibration.
Summit Racing - High Performance Car and Truck Parts | 800-230-3030 - Part# ATM-3788 $129.95
Although I haven't measured the diameter of the fuel gauge, it should fit in the panel without much modification.
Does anyone know who sells the lights for the gauges? It would be nice to see the fuel level when working in the dark