We will soon be installing porcelain tile in an existing bathroom and we'll need to add flange extenders. The original lead waste pipe is formed over the existing brass flange; the house was built in 1959 and this plumbing appears to be original. My local DIY plumbing supplier recommended cutting out this existing flange and replacing with new ABS - not a happy solution as I really don't want to disturb either the tongue in groove fir sub floor or the finished ceiling beneath the bathroom.
Should I fashion and shim around this existing lead to make the flange extender sit on top of this mess evenly or can I trim the lead flush with the flange? If I do trim the flange I’ll likely replace the brass flange with a fresh one. Is there a sleeve I can insert to direct the flow as this lead liner will no longer reach up to the bottom of the toilet?
Sorry for the many scenarios. A photo of the current flange with a temporary 3/8” sub floor in place is attached.