Yeah, the photo seems to indicate some paint over the upper surfaces of the engine cowl.
I have the Eduard kit in the stash that brings that plane as per that profile you added. It’s a very unusual Spitfire for sure, and that means it’s interesting!

What a great choice, my friend @lis!
I would be surprised if the top engine cowling would be unpainted.
Black is the most probable guess.

@johnb painting very logical and something similar was in Spitfire Vc. But in this case, I have no idea.

Truth is that with blurred pics you can never be sure about anything, my friend @lis.
Maybe the black portion was too narrow at the specific plane, maybe black paint was reflecting some light (the pic is admittedly blurred).
Of course, you can never be 100℅ sure, but rarely a bird carried an unpainted top.

Lis, answering your question- I don’t think the upper cowling immediately after the propeller is black at all. Looking at the photos, the area isn’t nowhere as dark as the blurred prop , and tbh it just isn’t dark enough to be more than a grey or brown tint in my opinion.
Quite likely I would paint it folllowing Eduard’s suggestion, meaning those parts came from replacement spares cannibalized from some damaged airframe.

@holzhamer thank you for your answer! I just purchase AZ Spitfire from my online hobby-shop

Found this pic at flickr, my friend @lis:

The profile rendition assumes that the top cowling is from another plane (as our friend @holzhamer pointed out, correctly in my opinion). According to the profile, there was some sort of oblique gray/green pattern at that cowling.

By doing some net research, I read that it is unclear why MJ250 was finished in this unusual natural metal scheme and, according the RAF Battle of Britain Memorial Flight (RAF BBMF) this picture is the only wartime photograph existing of this aircraft.

The never ending modeling research...