I put 34031 in iModelkit (iPhone app) and with Tamiya colors and it the recommends this ratio of colors:
XF74 (JGSDF Olive Drab) - 3 parts
XF1 (Flat Black) - 17 parts
XF2 (Flat White) - 2 parts
I can do the same thing for humbrol colors if you prefer, just let me know.