there is no proper way to do this. this is beyond unsafe. and is considered an illegal repair. (obviously not done by a shop so he's the one reliable)

this car will explode when hit hard enough. you never ever ever ever butt weld something like that together. there are several layers of structure there. and i will guarantee all 3 of those layers did not get penetrated properly. if i even thought about doing something like this, i would at least stagger my cuts and use some backing plates to splice this in. and not to mention im sure these welds have been ground down and the areas around the welds have been ground down. thus creating and even weaker point.

hopefully when this car falls apart it wont be around me.