Im replacing a 1920s vintage toilet with a modern 1 in one of my upper apartments. I was surprised to find that underneath the old toilet was a leadcloset bend attached to cast iron pipe. It looks to be sealed with oakum. The lead pipe is corroded & I popped a hole in it with my sawsall while replacing some damaged flooring. I need advice on replacing the bend & attaching it to the 4" ID cast iron pipe.