This 'G' gauge track measures out at 4' 8 1/2" from inside rail to inside rail.
This is standard gauge in 1/32 scale.
The rail weight (height and width) is very heavy for true scale, but the norm in this industry. I use lighter rail designed for 'O' gauge and hand lay the track on wooden ties for 1/32 scale.
My recommendation for use in a diorama would be to paint the ties and rail dark brown, paint the sides of the rail rust, ballast the track with scale ballast and then polish the top, or running surface of the rail bright.
This will give you a very good approximation of what you are looking for and the paint and ballast will minimize the oversize rail.
Ken