You are in a minefield here!
The various late war colours RLM 81,82,83 were introduced through various "Sammelmitteilungen". The problem is that the actual introduction of the colours is impossible to ascribe to particular production blocks,let alone individual aircraft. The various sub-assemblies were manufactured by many sub-contractors and assembled at several facilities. Everyone would use up stocks of earlier colours before moving to the new ones at differing rates. Also reality does not always reflect what the RLM thought was happening.For example RLM 81 and 82 were introduced officially at a time when RLM 83,previously unmentioned,was already replacing RLM 74.
I would do your aircraft with an RLM 81 upper fuselage colour (that area on which the fuselage balkenkreuz is painted looks dark enough to be RLM 81) maybe with one of the greens. I'd go for RLM 83.
The upper wings would be 81/83 or 82/83. I'd be surprised to see RLM 75 at this time. The model posted above has got a correct RLM 76/natural metal underside,matching one of the versions seen on wings built by Fiesler and Focke-Wulf.
Good luck!
Cheers
Steve