Stainless joins just fine with mild steel electrode, so pop a spot weld on there with MIG. It'll oxidize a little, eventually, but that would be that. I wouldn't bother with filler rod if TIG is an option, just fuse the material together in a few spots.
I agree that cadmium poisoning is one of the worst metal exposure illnesses we are aware of. Beryllium might have it beat, but not by much. Cadmium has been regulated in the US since 1972. I see it in certain electronics solder and chromate marine paints, but nothing newer than two decades. I think you would have to go out of your way to find cad solder today. Lead, on the other hand, is everywhere. You may not generate vapor at 425 degrees, but every time you touch it, you will get lead on your hands, and the thing we touch most with our hands is our faces, which is where our mouths are, and that's the way you chronically micro dose yourself with lead.