30+ inches to 40+ inches was the normal length for panoramas back then.
By color, I don't mean colorizing the photo so the uniforms are blue and grass is green. I mean that if you reproduce an old photo with black & white film or only black inks on a computer printer, it might resemble a Xerox . It will look better and more real when color film or multi-color inks are used. The original 1920s panorama would likely have a sepia tone to it-- so the original wasn't literally black and white ... I'm assuming your image isn't black and white.
Below is a color image of a sepia photo and a black & white image of a sepia photo.
