Need Prop Help

I have a 96 Nitro TF170 with a Mercury Force 90HP Motor. The existing aluminum prop has the markings almost worn off, and is in need of replacement. What I can see is that it is a "Sea Mark" 23 pitch. Numbers start with 760????? Anyone know what prop this might be? The prop has a "cloudy gray, smoky" look on it that can somewhat be rubbed off. This is prob not good. What caused this? Or is this normal? I want to replace this prop with either a new one to match the Sea Mark, or better yet, a newer compatible prop. I am told the LaserII ($$$$) is the best choice, but I dont know what dia prop is the existing Sea Mark in order to buy the right LaserII. Any thoughts?

Thanks in advance,

Dave