Still working on it. The what-if part is "what if Operation August Storm went on for another month." The Russians actually landed troops in North Korea and the Kurils in real life and actually did have plans for attacking the Japanese main islands with air assets I believe. However, they never got to that point because of Japan's surrender.
So with the current Japan terrain the what if hinges on saying the Japanese had not surrendered yet and the Russians drove down into the Korean noodleula (I need to have bases within striking distance of Japan).
Possible, and stress possible run date of "Operation August Storm" would be October.
And yes, the Russians would have P39Qs, Yak-9Us, La5Ns and maybe a smattering of La7s. Japanese would have Ki84s, N1K2s, and Ki67s. Still evaluating other planes for each side (A20s, subbing in the B25H for an earlier B25 with rear guns, etc.).