It perhaps should be stated (the obvious?) that I believe the warbirds already flying today that are appropriate to have such a propeller fitted, already do, such as in the form of the Gloster Gladiators and the Hawker biplanes. I don’t think any of the Hurricanes/Spitfires flying today, even the earliest, ever operated with a two-blade Watts propeller originally (in the case of Spitfires P9374 and N3200, they are fitted with the rare DH bracket propeller, as they were fitted with during original service/to the end, and was the type of prop that R4118 and P3351 also had originally as well I believe, if I recall correctly).