I think that Jacques and his Russian team have a clear idea about Russian LL. BTW, a first LL convoy has occured in FFO in July 42.
The Bulgarian air force has to protect Ploesti, the Romania fleet is not a real threat (there are still no German MTBs and German/Italian subs in the Black Sea), the Soviet fleet will keep his bases, the Allies contest the northern Aegean and Turkey is in a good mood towards the Allies.
So convoys through the Black Sea are quite safe IMHO ...