Sorry no rpm records. I rarely use a tach and when I do I rarely keep records. Use it as a tuning tool but mostly tune by airframe performance. I understand completely your prop requirements for the WW1 plane. If it were mine, I would start out with a 26-10 because you know it will work well on that engine. After some flight time, you could certainly switch to a larger diameter prop. Maybe something like a 27-8 or 28-8? Xoar makes some nice WWI props. Several styles to choose from. One thing for sure, the 75 would not be happy with those prop sizes where the 85 would love them.