One end of a lead bend has a brass feral wiped to it or at least the ones I get do. You can put a no hub clamp on that and attach it to whatever you want.
I do lead bends fairly frequently. Here commercial buildings can not have any plastic pipe, everything has to be cast iron or copper. Their is also one town which forbids plastic waste lines altogether. Their certainly isn't anything wrong with using them when the situation calls for it. They last a long time unless someone gets overzealous with a toilet auger. They're easy to repair too, just clean it up well and throw some new lead into and over the hole and it's good to go.
I agree thought, I can't see any reason to use a lead bend in this situation. You do know that you don't just fold it over right? You need to hold it out without ripping it then solder it to the flange keeping the flange just hot enough to melt the solder but not to hot that it's going to melt the lead bend. Remember while doing it don't touch the lead with the flame, heat the brass flange.