I came across this subject a few years ago when making a model of an A6M2 also. Pretty much most box arts and some books depicted them as a white / ivory colour as was done in most movies too.
In reality, it seems the actual colour was a more off coloured caramel / sky / beige that is closer to for example early RAF aircraft undersides (See Spitfire / Hurricane Mk I for example).
The "Brilliant White" colour doesn't seem to have any historical backing. Most airworthy or museum aircraft are now represented in a more true colour.