Thanks guys for the comments!
I have been doing a ton of research and I was (suprise!) wrong about the date, possible colors and insignia of the F6F that O'Hare took posession of while commanding VF-6 in 1943. Apparently his was one of the first batch to leave the Grumman Iron works and was finished in the then standard intermediate blue over grey with the star in an insignia blue circle. Planes were repainted at squadron level later. So, repainting will be in order, after the F-8 is done.