Holley 1920 Rebuild Help

I have found that the gas evaporates and float weighs less. It may last about 2 days, then will float like a rock! One problem is the modern additives in gasoline to keep injectors clean. They are hard on many materials and hoses in older cars. One solution I found is to use a brass float, however that may not be available for the 1920. The BBS carb does have a brass float and a carb conversion is possible.