The common problem with these KMT wins the civil war threads is the assumption winning means Communism disappear from the country. That wont happen unless the Communists were totally defeated in the 1920s. After WWII the best the KMT could do is contain the Communists to Manchuria. Communist China definitely supports North Korea’s war of unification. They can’t afford Korean unification under American allied regime. Mao probably throw in early and invade South Korea along side North Korea. US may not intervene in this scenario given the odds are overwhelming and no domino theory. Korea is united under the Communists. Soviets establish naval and airbases in Korea. Nationalist China demands the French out of Vietnam and backs a friendly anti-Communist regime. Ho Chi Min fights a war of insurgency, but probably loses cut off from Soviet aid. US designate China as a major ally to supress Communism in Southeast Asia. The occupation of Japan lasts into the late 1950s like the occupation of Germany. Communist Chinese and Koreans infiltrate to stir up revolution there but this is successfully defeated. Soviet military support for Communist China results in another civil war the 60s or 70s. It would look a lot like a bigger Vietnam War with Communist guerillas fighting government forces in central China. Soviets deploy combat aircraft in Manchuria and Korea to defend their airspace. US may end up direcly involved with ground troops and eventually withdraws in frustration. However “Vietnamization” of KMT forces probably succeeds as the much larger Nationalist China should be able to handle it with American weapons. The war ends with status quo ante bellum because Soviets threaten war if Manchuria is invaded. An uneasy peace is maintained. With the end of the Cold War, impoverished Communist China collapses and the right wing dictatorship of Nationalist China liberalizes, resulting in reunification in the 1990s. The economy takes off afterwards. Overall present day ROC is comparable to TTL PRC in development and overall GDP. Economic advantages of capitalism in the south is offset by decades of highly destructive civil war. OTL ROC may not be fully democratic but have some sort of managed democracy like Turkey with some similar Erdogan like strongman questioning the continued value of alliance with Washington.