Hi FR,
sorry, I don't know the answer but till someone comes with it here are some tricks to start.
Make a your own drawing in 1/87 as better as you can, using the drawing and dimensions of the first photo in the topic.
Use an appropriate photo to make an estimation of the unknown parts
knowing the frame side height from the drawing you can make a close estimation of the tank height
the same applies comparing the wagon and tank length or every other part.
Keep in mind though that at the photos there are lens distortions so stick to the scale drawing measurements.
At the photos we use the relation between "measurements". For example we count how many times higher is the tank compared to the frame side, then multiple that number with the frame measurement from the scale drawing
I hope that was helpful
And keep in mind that at the end it is right when it looks right