With one more year to prepare, we can probably consider that the AVGAS problem is not as acute as it seems. The Soviet airforce was certainly not expanded without making AVGAS stocks either ...
Naval infrastructures have been improved too.
With Allied holding Limnos and contesting nothern Aegean and a more friendly turkish attitude, mining Bosphorus would be difficult (BTW, the Black Sea fleet has quite a lot of minesweepers).
I had once a document from Jacques which summaries what the Soviets could do with one more year. But unfortunately I don't find it anymore ... :(