Your challenge, should you choose to accept it, is to have the French and Italian communists take power peacefully by 1970 with a POD no earlier that the Potsdam Conference.
Darn. If the POD hadn't been that late, I would have suggested a failed D-Day for France, as the Soviet Union woiuld have marched in to take them over. Perhaps that would have worked from Italy as well, if the Allies had lost in North Africa.
I can see this, even with a D-Day that works, if the US imposes AMGOT in France and arrest De Gaulle for interfering ( don't laugh, it almost happened, but the MP asked for confirmation of orders from HQ when they found De Gaulle surrounded by french civil officials ), but Posdam is too late, I think.