This is a second floor bath, branch:
Old vanity was bottom left in pic, old tub was to right. Top left is a run to a vertical vent behind wall up through roof. Tub and vanity are wet vented (I think) for that short 1 foot between Ts.
Plan is to retain toilet location rotated 90 degrees.
Will put double vanity to right where old tub was.
Will put curbed shower back behind photographer, down in photo.
I do not believe I have trouble with supply - debating running 3/4" for hot.
I will run all appropriate vents for new vanity and shower. I'll get rid of drum trap.
Question is - current drains are 1 1/2 inch - how do I reconfigure for shower drain? Ideally, I understand, I'd run 2 inch for shower. (Local code is latest IRC allowing 1 1/2" for shower if less than 5 (or so) GPM supply.)
As you can see - current stack is cast. It seems to be in pretty good shape. But the idea of getting that interesting 3 x 1.5 x 1.5 x 3 cast piece out is a little daunting. Then I'd have to oakum/epoxy a 3" PVC setup.
Or, I could remove whole cast stack.
Or, I could leave that "interesting" piece and live with 1 1/2" shower trap that will go through a u-turn to get into that "piece".
What would you do?