1953: Reformers get Poland, Traditionalists get Hungary
The Central European Revolution of 1956 happens in Reverse, but with Poland going further, fighting harder, and Hungary joining in too.
This results in a reforming faction in the Political Committee, with the help of Zhukov, ousting those who would later become the "anti-party" group of our history.*1
The revolution rammifies into the USSR itself, reversing in many places the loss of working class power during the Great Patriotic War, and in some cases restoring the balance of forces of the early 1920s (particularly in Leningrad).
Western Europe goes nuts for the next 20 years—mainly as the PCF and PCI are now "off the hook" as far as their revolutionary factions go. France, Italy, Portugal, Spain in that order. The British ultra-left is larger than in the 1920s, more democratic than it had been since 1921, and forces the Labour Party left.
The influence of workers democracy in Europe means that the Chinese, Korean, Vietnamese, Laotian and Cambodian movements have a lot more oversight over them—the gang of four is unlikely to hegemonise pissed off youth in China. These effects are largely positive given the influence of agronomists in Poland and Hungary in terms of new post-1956 humanist socialist ideology.
Workers control also ups productivity levels at plant level, and in comparison to the Soviet style societies in the 1960s and 1970s over system wide economies.
So it is a win by default sometime in the 1970s when the Central European Commonwealth offers to help mediate the political and economic crisis in the United Kingdom (probably also by simply supplying direct economic aid to the militant unions). The US's access to European markets and capital is so restricted that it can't sustain 1950s or 1960s rates of military expenditure and retreats towards a kind of isolationism combined with labour discipline through super inflation. (If this happens early enough, you might get Chile surviving).
yours,
Sam R.
*1 Chief improbable point—no PC is going to accept a Poland outside of Soviet control for defence purposes. On the otherhand, Gomułka might be willing to use the Polish military to achieve a costly stalemate, and such a stalemate could credibly cause a rethinking.