Mark,
I would go with the figures in the text which I believe is 50mm and 146 mm respectively since the picture is of the Katana. The spinner size is around 3 1/4" but you might get by with a 3" nylon in yellow. Would look good and a lot cheaper than aluminum but not near as good. As far as hardware the control horns look a little small and I intend to at least use larger ones.

I hate the color scheme. Mine had wrinkles and bubbles in the covering too. The paint on cowl does not match plane.
Erick Royer has done some recent mods on his Staudacher in the review. I will mount my servos in the fuse near the wing tube and run pull pull on rudder as he did since I will be using a light glow engine. This should eliminate the need for nose wt.
Luck & Happy Flying,
PilotFrog