What did they plan for this bsmt bathroom?

[Basement]

Hello,
What was the original plan for this basement bathroom?
(Photo attached).

https://preview.ibb.co/dPuj0n/bathroom_1.jpg


I am not sure what the original layout plan was. I put my best guess. The main stack is exactly 12" from the center of toilet, which does not leave room for drywall. 1970s house.
The walls are not secured to the floor yet and can be moved or changed.
The 2x4s' are about 31" apart. to show space required for standard toilet.

Any help identifying would be appreciated!

 

[TomFOhio]

The toilet will work with 1/2 drywall. The sink will get an elbow off that tee and stub out for the drain. The shower they didn't do correctly. You will have to break up the floor around the drain in order for the shower drain on the shower to set flush on the floor. Most shower drains are 2". That's how they are roughed in. When you open around the shower drain make sure there is a trap on that drain before you set the shower in. Hope this help you some. Let us know.