That looks to be the "shiny case" version of the Fox.35. In years back when Fox racing was gaining in popularity, this was one of the desired versions to have, if I remember correctly. Notice the front of the head is clean compared to the rest of the head? It's been sand blasted by dirt and grit in the prop blast while sitting waiting for launch! Bench run it with a 9-4 or 9-5 prop to see how it handles and needles, with no muffler. If it starts, needles easy and holds a setting, and the exhaust comes out clean and clear, it should be broken in. A couple of tanks of fuel should be enough to tell. Mount it solidly on metal plates between the engine and the mounts, and with the tank slightly higher than the center line of the engine, and you should be good to go. Start out with a 10-5 prop and experiment with the different brands, maybe even a 10-4. The perfect prop for that engine is the one that works the best! When you settle on a prop size and brand, get six more for your flight box.
Good luck and have fun,
Dan McEntee