Old gas questions

As the fuel evaporates in the line, whatever is left keeps gravitating to the lowest spot in the line, as it gets thicker and thicker. It eventually becomes a syrup, and finally solidifies. I have tried every chemical I could think of to soften that junk but once it's like that,it's like cured JB weld.
That line has been breathing for 25 years, less however long it took to evaporate. Breathing with every temperature swing, season, and barometric change, pulling in water vapor with it.And that water condenses and collects in the lowest spots, usually under the passenger seat. So that will now be on top of the varnished gas. The water will be gone, but the rust won't be. And as the new gas comes thru, it will wash the dust out, leaving the pits.... which could easily become holes.
If nothing else, I would cut those 3 or so feet out, and install at least that much new line, with fresh,flared ends.
The problem with that idea is that if some day your flares leak, the pump will suck air, and give you fits trying to figure it out.