McKay,
I'm looking at Detail and Scale #55. It shows the bottles you are refering to plain as day in a black and white cockpit shot (XF4U -1)with the seat removed. Color photos don't give a hint of what color those @###%&*#@ things are, because, as you say, they are behind the seats. I'm pretty certain the O2 is green and not a lighter color based upon the darker hue of the bottles shown in the b/w photo. Red was used for fuel related fixtures (filler caps, fuel line color coded tapes, etc.)
while yellow was for oil ( that great big container forward of the fire wall).
No wonder the windscreen got fowled when the oil bucket got hit.
I'm still reviewing my soures and will send along anything I find. Heck,
by the time I get done ,I may as well build a "Corsair" too.