I picked an industry to switch: The Arm & Hammer plant at Old Fort OH. Here is a satellite photo of the area. Of course, you will have to extrapolate what the buildings would have looked like in the late 40's. The operations I suspect would have been pretty much the same. Anyway, I can make out covered hoppers, boxcars and tank cars and maybe gondolas off the picture I show. There is a two-track line running east and west into Old Fort.
Here is the area:
Obviously we can't do the entire plant, but we can take two of the more interesting sections and compress them together. The first part is the very end of the track at the bottom of the picture above. The second is the area where a couple tracks diverge off to the west of a big square building near the "top" of the factory buildings.
I rotated the images to match the orientation of the plan. Notice in the first picture there seem to be two types of tipples. The one on the far right for loading tank cars. The one on the left for loading covered hoppers. In the lower picture, you see tank cars on the outside of the square and box cars on the inside of the square, making me think these are raw materials.
As you can see, the two areas are compressed by both location and number of tracks. But you can still get the feel of the operation. Your job will be to find out what they made at the time of your layout and what kind of raw materials you would need to run the operation. They seem to make kitty litter now.

I would suspect baking soda, industrial bicarbonate of soda, and possibly fire retardants.
Operations would be run from one of the outside tracks probably the one closest to the edge of the layout. This is where you would place outgoing and incoming loads. (fiddle track) You would take box cars from there and set them along the left side of the track closest to the buildings and bring the empties down for returning to the RR. Full tank cars you would spot at the building at the lower right of the layout.
Likewise you take empty tank cars and hoppers to the appropriate tipple, fill them and return them to the RR.
Edit: I finally figured out why every thing in the photo is so white--decades of spilled product. Will be adding grass and roads. "Dirt" roads along the tracks seem to be a reddish brown clay or gravel.