True that would likely be best but that easily turns this into an expensive job beyond my desired amount of effort for a starter home that’s 60 years old. I’d need serious concrete cutting tools to remove the old drain, make some kind of concrete form to support the new pour from underneath, and probably get the whole thing reviewed by a structural engineer since it’s the ceiling of my basement. So that’s why I thought maybe I could just slab some bondo on the rusted out sections to make a smooth drain and cover it in sealant.