I guess my question would be…..what are your plans for the car? Resto? Drive and enjoy? Race car? If you’re just going to drive and enjoy it, you don’t even need to fix that. Just put a new package tray liner on top and go about enjoying the car. If you’re going to restore the car, do it right. Drill out the spot welds, find a rust free package tray and weld it in. Hacking it in with some metal to me is an exercise in futility.