10R80 is robust to begin with, much stronger than a 6R80. The fact that they only needed to switch to a 4 pinion output planetary to pass all durability requirements is proof of that.
The 10R140 would be massive overkill, it weighs 110lbs more than a 10R80 and is designed for a GCWR of 50,000 lbs. It’s not just a 10R80 with larger components, it’s a different transmission all together.
As far as the torque rating suffix, it’s used more now for just classifying the transmission than actually defining its torque capability. By designation alone, the 10R140 is rated at 1032lbs of torque, yet the new H.O. Powerstroke is rated at 1200lb-ft.