O27 trains tend to be undersized (by up to 25% in the case of postwar), but even if you assume 1:64 scale for O27 trains, the HO structures, at 1:87, will be about 20% undersize.
That said, S scale hobbyists often do use some HO structures on their layouts for lack of anything else to use. If you can disguise or obscure or change details that give away the actual scale (such as doors), you may be able to get away with it. I've driven past steel mills before and frankly I don't know if I would notice if a steel mill model was grossly undersize, personally.
Have you been able to see the Walthers steel mill structure in person? If possible, I'd give it a shot, setting an O27 train next to it so you can see if the steel mill dwarfs the O27 train like a real steel mill would dwarf a real train.
Just my opinion here but the difference between O and HO is pretty large. A technique used called "forced perspective" puts smaller buildings in the background since that is the way things work in real life; the farther away something is, the smaller it appears. So if you have a large layout and put that mill in the distance it might look okay. But a steel mill sort of begs to be in the foreground, my opinion again. I don't see a way to have 027 cars running around near the structure though but maybe someone else on board here has ideas.
Welcome to the forum too! A lot of knowledgable folks around to assist you as you enjoy this fun hobby.
Jim
I'm a novice but desire to build a steel mill layout featuring Lionel O27 track and trains. I like the Walthers steel mill structures and wonder how HO buildings would look with my trains. Can these buildings and trains coexist?
I should note that I'm building on a 4x8 sheet of plywood. I guess I'm more concerned with an overall "theme" for the layout.
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