Nice, unusual subject, and a decent size mrdj
You could go with a Ramoser varioprop 5 blade hub (12C hub), and Ramoser scale 15.2" blades. Not exactly cheap, though. Sorry, haven't looked at suitable motors.
If you decide to scale it down somewhat, Manzanos 5 blade hub
for the FSK blades
would be a good choice. Sparky used the E-flight 480 910kv motor on the 6 blade version of his YO-3A, so one less blade and slightly higher kv should work equally well.