The camo scheme was a quite typical for the period of the Great Patriotic War ( the Summer 1943) . It consisted of AMT-6/A-26M Black ( Tamiya XF-1, Testors 1749) but the colour should be of a little bit of the grey tonality, AMT-4/A-24M Green ( Testors 1715/1713, Gunze H58/H303) at top surfaces. And the AMT-7/A-28M Blue ( Testors 2123 ) on undersides. Samples of these colours in the first set below.
But I would suggest using those of the second sample set with their tonalities in below.