I would suggest the players be USA, Japan, Britain, USSR, Nationalist China (Republic of China) and Communist China. The Philippines should be US control and contain at least 1 SC (maybe 2). I wouldn't have the US mainland be in the game - Alaskan islands as an SC would be fine I think but the mainland stretches it too much.
I would also stretch the map west a bit to include eastern India and Burma. For SCs:
USA: Honolulu, Philippines, Midway, Guam, Aleutian Islands
Japan: Tokyo, Kyoto, Korea, Iwajima, Taipei (Taiwan)
USSR: Vladivostok, 4 other eastern Russian cities
Britain: 2 in Australia (Sydney, Canberra?), 2 in India (Calcutta/Bombay?) and Singapore.
China: 4 SC
Neutral armies in: Indonesia (several, Dutch holdings... Sumatra, Java, maybe a neutral fleet supporting hold, Borneo)
Neutral armies in Communist China (northern/northwestern-ish, forget exact areas, should be 2+ armies)
Manchuria should be a Japanese-colored territory with a neutral SC - sort of like http://vdiplomacy.com/variants.php?variantID=12 with China.
Neutral SCs: Burma, Saigon, Malaya, Manchuria
Importantly I think less neutral SCs= better. The only true neutral SC I see are the Dutch holdings in Indonesia, French holdings in Indochina, Communist China, maybe Mongolia.