could you change the sending unit?
What ohm range is the sending unit?
I just changed a swing arm unit for a marine unit. The marine unit has a float around a shaft not a float mounted on a long wire arm. I think this is a better sending unit than the ones I've used in the past. Much better. Easy to test before you install. No removing the unit and bending the arm to get it to match the gauge.
You measure the depth of the tank and order the sending unit to match.
here is a link to one on ebay
Moeller Reed Switch Fuel Sending Unit Pick Size | eBay