72 Duster with a Rusty fuel system....how do I avoid this???

I can get NON ethanol fuel but it sure isn't easy to find. Race gas here is NON ethanol and it runs over $7.00 per gallon.
I'll get some of that "Sta-Bil" and fill the tank up. I have a collection of stock fuel sender lock rings. I also have several stock sending units that look terrible. I tried checking them with my handheld electrical tester. I had some strange readings so I think I was on the wrong setting. I'll check the new sender when it arrives. Thanks everyone, I appreciate the help.