Chiang wins:
Territorial changes: Chinese invasion (reconquest) of Tibet and Sinkiang. So OTL territory + Taiwan.
Outer Mongolia would remain a Soviet puppet. USSR would never give that up, didn't give it to Mao, would be the same with Chiang.
Chinese expansion anywhere else is ASB.
Chiang would probably take a neutral stance in the Cold War, taking neither the US nor the Soviet side. Stalin would be quite happy about that.
Why do you assume neutral stance?
I would think after defeating the Communists, who would probably have still recieved aid from the Soviets that Chang would be ill disposed towards the Communistic Soviet Union.
Also that the US nuked the Japanese, which would have to put the US in a more positive light.