This looks very nice Spiros. I built my Hasegawa "Val" many years ago, and I used a very light gray color on it. Now I know that mine is painted wrong, and someday I might go back and give it a fresh paint job with today's better understanding of the various colors that were used by Japan during WW2. This is still an ever evolving field of study, and new things are being found as more people start researching this fascinating subject.
From what I have read on the various colors they used on these "Val" dive bombers, they started out with an overall color very similar to that of the early A6M Zero. It was the same color on the top and the bottom sides and was similar in appearance most like a FS-24201 color or a little darker, towards FS-16160. These are some color chips scans I made from my FS color book. It looks darker in the paint chip scan and depending to what your light source is the overall look can be different.
Then as time went on, in the field they applied various greens over the top of the original color. The green paint would occasionally chip away exposing the original color underneath.
As the later planes were being built, they were being painted at the factory with the upper surfaces green, and the lower in gray. So it depends on what time frame you are going to chose as to what your plane could have looked like.
Here's a few links that might shed some light on what I'm trying to describe to you.
http://www.aviationofjapan.com/2009/04/aichi-d3a-val-interior-in-detail-colour.html
http://www.aviationofjapan.com/2009/04/aichi-d3a-val-interior-in-detail-colour_10.html
http://www.j-aircraft.com/faq/D3A.htm
http://www.j-aircraft.com/research/jimlansdale/pearl/jimlpearl.htm
This is how my "Koga" or "Akutan" Zero looked after painting it in overall FS 24201 color. I now realize that I will have to go back and add a single yellow stripe on the rear of the fuselage... some day .
Hope this helps you along the way.
