Recommendations for New Fuel Tank

Took the fuel tank out to paint the bottom of the car, but heard hard objects sloshing around. Looks like rust inside, and lots of buildup. Seen new tanks advertised online for about $200, so I am thing of purchasing rather than trying to unsuccessfully clean the tank. Anyone bought one of these new tanks? Any seller recommendations? Any way to treat a new tank to prevent corrosion / build up?

I ask this because in prior years I had old 1960s Volvos, and even after sitting for a while, the inside of the fuel tanks were like new. Not sure if those were aluminum and the Darts are steel.

Thanks much, It's cold in sunny SoFlo today.........