If you have a welder then cutting it out and replacing it is the best way. If you do not have a welder then cutting it out and fiberglassing it may be an option if you do not have the means of doing a permanent repair. The fiberglass would be a temporary solution but would get you driving and provide a surface for your weatherstriping to seal against. POR is a PITA. Use Zero Rust instead especially for this applciation.
