Hi,
IMHO, La-7UTI prototypes were painted in standard prewar, 1940 scheme:
- upper surfaces were "Protective" green
- lower surfaces were Light blue
it is known/confirmed that other postwar planes have been paintad in the same scheme: Il-10, Yak-9, Tu-2.
Solid dark gray AMT-12 or solid blue-gray AMT-11 for upper surfaces were never official schemes (probably exist only on Pilawskii's drawings).
This is very possible, anyway it doesn't exist only in drawings of EP. Here is an article from M-Hobby
http://scalemodels.ru/modules/forum/viewtopic_t_954_start_220.htmland a color table from it showing a grey-blue Yak-3
http://postimg.org/image/s89av6o4/Regards
Massimo