Hi Tom,
I had the same issue when buildind the same kit a couple of years back, (after picking it up as a second hand item), being an IJ Army bird, the interior is the opache green, I mixed a little Humbrol clear Green to Humbrol Aluminium to get my interior colour, the undersurface is IJA Grey which I used from the Tamiya range, The Mauve upper surface colour is from the very old Humbrol Authentic range of Japanese colours. The prop is a 50/50 scheme of Black on the inside blades and Aluminium on the outer part of the blades.
I hope this helps a little with your 'Sonia' project