On my keyring, I have one of those little flat Craftsman things that have 4 little regular screwdriver tabs on it. It is the oldest looking one I've ever seen. It used to be on my dad's key ring and I remember it looked pretty old when I was a little kid.
So, I understand.
If you are in the Chicago area, I likely have something you can have as a donor.
Do a search on fender washers on here or fixing leg sockets & you'll see what people normally do. You might want to try some sort of modified fender washer sort of thing because the bowl is so bad. You might even just try cutting off the tabs off a donor kettle & leave PLENTY of the old kettle attached. Then, basically do the fender washer trick through the portions of the donor kettle that you leave attached to the donor leg sockets & attach that to the outside of a decent portion of the original bowl. In other words, cut a large enough piece of the donor kettle surrounding the leg sockets so that you could attach that piece of the donor kettle to a solid piece of the old kettle with a bolt, washers & a nut. If it (or something else that you think of) doesn't work, you can always go back to trying the whole welding a piece into the kettle.
Good luck.