I'll be very curious. To get an idea of the "hardness" of the rubber, try to press on the thick area of the windlace piece you currently have (the area between the bottom of the part going in to the retaining piece and the top). What I have is in my opinion at least 90 and possibly flirting with 100. About as hard as a pool ball. 40 would be good...45 might also be ok and even 50 might do. That scale is funny.
