The expense to try to fit a fuel level float into a tank that was not designed to hold one is the first hurdle. As to the gauge yes that electronic one posted may work but you still have to somehow install a float level sender in the tank, and get one that will fit your tank (if you could find one) and then it has to work properly without any.. Or you can order it directly from the manufacturer, LSK Motorcycle Electronics, www.lskelectronics.com which is based in the Czech Republic. This device says it "measures the hydrostatic pressure and computes the level of the fuel in the tank, or the actual amount of fuel - according to the mode you select.
Universally usable fuel level sensor that allows to measure the fuel level without need of the float in fuel tank! Device measures hydrostatic pressure of the fuel, computes the fuel level and sends the corresponding signal to your OEM or aftermarket gauge.. Universally usable Fuel gauge with level sensor that allows to measure the fuel level without need of the float in fuel tank! Device is designed to measure hydrostatic pressure in fuel hosing. Device can be calibrated to compensate the shape of the fuel tank and shows real amount of fuel in the tank.