Keep it or cut it? Rust question

[Old Chevy Lover]

Had a question that I wanted to ask.. On my firewall, the lip has rusted pretty bad. It is all there, and I could probably weld and grind and weld and grind to get back to decent condition, but was wondering what everyone else suggests.. Work on it and fix it, or just cut it off, and smooth it out. I am posting a couple pic's to show what Im talking about.. You will see the 'holes' (I circled them).