I am replacing my toilet and after researching I found the flange is covered by a lead riser that is bent, folded, over the flange to hold it down. I unbent it so I could remove the flange before I read what that was. Should I put the flange back and peen down the lead? Can I cut the lead down to the floor with a Sawzall and put a PVC Oatey that has the expanding ring flange? Or, do I really have to remove the whole thing down to the cast iron pipe, add new PVC pipe insert, etc.?