In my now-revised model, I have the west pipe on the line that runs out from the edge of the masonry opening. This is based on a new method of photo-matching I am experimenting with. I have not received measurements from the Museum which will remove all doubt.
My distance from the masonry opening to the
west east wall is 32". Yours is probably different based on how the model was built. Measurement for the east pipe go to the pipe, not the coupling on the floor.
In an earlier version of this, I incorrectly placed the line on the floor at a right angle to the floorboards.