Thanks to all for the info. Stik, I had read somewhere (don't remember when or where) that the "Neutral Grey" used today is different than the shade used way back when. Thank you for confirming the same thing I was thinking in that the modern version is lighter while the one used during WW2 was darker.
GMorrison, the ANA 603 looks pretty darned close to "Gunship Grey". I think what I might do is mix up my own batch so that it's somewhere between Neutral Grey and Gunship Grey. I'll just mix it 50/50. Indecision is the key to flexibility! LOL!
As for fading, I was going to keep the weathering to a minimum. My thought was that the Pearl Harbor P-40s were probably kept in hangers more than they were left outside. With it being peacetime, I can only imagine there was more time and resources to care for, and store, the aircraft. I figured I'd add some oil streaks and some light foot traffic scuffing but that's about it. I fear that if I try for anything more than that, I'll probably screw it up anyway.
Thanks again!!
Eric