Finland gets what it deserves for being a nazi ally and gets completely taken by USSR
USSR keeps Finnmark and Bornholm which the Red Army liberated
USSR liberates whole Germany and Austria since the rest of the allies were slower
Partisan Resistance wins the Italian Civil War and takes power
Partisans win Greek Civil War
Albania and Bulgaria join Yugoslavia which also gets Carinthia and Friuli-Venezia Giulia as planned
I imagine OP was thinking of Cyprus doing enosis with Greece, though I don't think that's something that the British would allow for in that time period, and definitely not in this scenario.
On the topic of San Marino, they actually did turn communist! And they were that way until 1957, when the treacherous social-democrats and christian-democrats overthrew the democratically elected communist-socialist government with the aid of Italian tanks! (source is in Polish, sorry, try to bear with a translator)