I am remodeling a single story house built in 1902. The 4" cast iron waste stack serving the bathroom is in the basement and originally had a stack vent through the roof, while the horizontal branch for the bathroom is in the crawlspace. All the cast iron was taken out except a stub into the basement floor for connecting a new pvc system. The exterior walls are soft brick (no framing) and the interior partition wall is flat framed lathe and plaster; long story there is really no place to run vents in the bathroom area and I'm really hoping to avoid re-running a vent stack again if possible. I have one place on the opposite side of the bathroom where I can box out a vent stack so I'm hoping to do a wet vent system based on IPC section 912 with an air admittance valve at the sink. I still have to drop the stack vertically once its on the basement side to tie into the existing line... do I have to (by code) or need to (recommended) vent that section? (it would be the white vertical pipe in the images). What I'm not seeing the code is can I bend a soil/waste stack so that it goes vertical without needing to make it a Stack Vent? Any advice/help appreciated!