If the corsair is out, about 6 months late for Midway, then my option would be the P39. at the altitudes that were faught at Midway, if USMC pilots were able to use the zoom and boom tactics that the flying tigers were already using in China, the P39 has a large top speed advantage over the zero. If a large quantity of p39s were stationed at Midway, operating from the land base there, I think that so long as they didn't dogfight the Japanese fighters in slow turning manouvers, the P39 would have made a vast difference. Although not considered very successful when used by the US in Europe, the P39 did gain some success in New Guinea, when helping to defend Port Morseby
Did the P39 have good range?