I had one of those motors in my back yard in Texas. It was left behind when the cotton gin burned down. I purchased the property and inherited what was left of it.
That looks marine, with what is possibly a reversing drive on the right. Two stroke, diesel or "semi-Diesel". I think I see what might be preheating burners on 3 of the four heads.
edit - Duh, of course it's marine, there's the telegraph at the flywheel end.