Devil, thanks for looking closely and mentioning your thoughts - you made me pay closer attention and I caught something else that is off - between the photos and profile - I need to move the "R3" to the rear, closer to the insignia. I relied on the profile for that spacing and its clearly wrong.
Regarding the black section, I take your point about the illogic of the color black, as the IL-2 skin and Eduard model box cover show. I'm not convinced its a prop shadow, but I wonder if it could be a replacement front cowl ring, with a newer/darker OD green - perhaps the same shade used by the 56th FG, that I used on my 56thFG "Pat" P-47D-25. "Dorothy K" did originally come over to the 373rd from the 56th. The dividing line between dark and light appears to be midpoint on the left lobe of the heart, and this is pretty close to the boundary between the cowl ring and the other cowl panel sections.
What if I just finished it with a newer/darker OD green in that section, instead of black? The width of the darker color would be about the same as the red band on "Balls Out", pictured above...
Thanks for helping me get this one right!