Besides the belly window early production -1A's had a couple of other features normally associated with the -1 birdcage - those being the short tail wheel strut, and cowl flaps that went all the way around the cowling. VF-17 got the first -1A's off of the Vought production line, and many photos of their -1A's show the full cowl flaps and the short tail wheel strut. Changes were not always implemented at the same time, an example being Ike Kepford's second #29 had the later cowl flap setup, but had the short tail wheel strut. I believe that one of the resin aftermarket companies will be doing a set of full cowl flaps for the Tamiya 1/48th -1/-1A/-2 kits. One thing that VF-17 did on it's own was to retrofit most (if not all) of their -1A's with Hellcat props, which I believe is the same type of "paddle-bladed" prop eventually standardized on the -1D.
As far as 2-tone paint on -1A's goes, I doubt if any ever came off of the Vought line that way. I have seen many photos of 3-tone Corsairs that were so badly faded that they were virtually 2-toned. As mentioned above, VF-17 got the first -1A's, and all of the ones I have seen photos of were 3-toned. Also, have seen photos of some "factory fresh" -1 birdcages that had the 3-tone scheme. Come to think of it, I have seen photos of some New Zealand F4U-1D's that kinda looked 2-toned !
Jim ( starting his Tamiya -1A )
Most of us are acquainted with at least one "know-it-all". He may be as close as the mirror. [}:)]