I am doing a bathroom remodel in an 1888 house and am having trouble figuring out the correct toilet flange. The big issue is that there is a steel beam which runs perpendicular to the 3" drain pipe, which limits how low the drain pipe can be placed. I have tried a 4" x 3" reducing closet elbow and cut it off (~ 2.5") to the correct height, but now a flange won't fit inside it. The only elbow I can find that will match the finished floor level is a hub to hub 90 elbow (see picture). I can't figure out how I can install a toilet flange to the hub side. Any suggestions?
Paul