wow.. good luck getting that to shape up like it once was... an alternative is to weld in a new section, then blend the seam sand/paint.. that spot has some serious curves to begin with..
but essentially you have the process down - sand , dont have to go to bare metal but if you want to then make sure you hit it with a self etching primer on top of the metal.
then use a primer sealer to well, seal.
paint, clear, enjoy

that might just be as much work as what im doing...

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