OK, here's my attempt at a map. The "British/Commonwealth" zone is roughly like in OTL, as is the American Zone (on Honshu). However, the difference is simple. Whist the "Imperial capital" is still Tokyo, the American zone is run out of Kyoto, whilst the British/Commonwealth zone has its joint command HQ at Fukuoka (Hiroshima and Nagasaki having been blown up, and are in their zone). The Soviets and Chinese have their zones as outlined above, with the exception that China annexes Taiwan and makes it a province. I don't know what to do about the Ryuku islands (represented by Okinawa), though.