That sounds like a fantastic modification for the John Deere 9000s Series in the game. The addition of American signage, numbers, and decals adds a touch of realism for players looking to immerse themselves in the American farming experience. The option for duals with fat rears or singles with fat rears also provides flexibility for different farming needs and preferences.
The increased power to 770 and a max speed of 40 will surely enhance the efficiency of forage harvesting tasks in the game. Additionally, the price of 499500 seems reasonable for the added features and capabilities that come with this modified version of the harvester.
Overall, this edit appears to be a well-thought-out enhancement to the base game's 9000s Series, providing players with more customization options and a more authentic American farming experience.