YS, the primary QRA target for Plan B - at least 5 aircraft - was Leningrad. At that time there were only 7 aircraft of QRA. Draw your own conclusions.
Moscow would have been in range for aircraft with the double-tank fit.
At one point it was planned at that one route for Leningrad would require a single drum tank. This was seen as a severe technical limitation as it required that one QRA aircraft at Waddo and a spare were both so fitted. At the behest of the stn cdr I had to get Bomber Command to change the routing.
That particular mission was routed through the back door so to speak.
The survivability quotient for was pretty low, but by that time did it really matter?
Probably not, but it was the question of the British psychic. I believe our near allies were not as picky. I know when NEAF introduced a new plan that meant we had only sufficient fuel for post-target plus 10 minutes flight. It brought a gasp from the audience when we were briefed and we were not happy bunnies. Logically it would have been no worse than landing in Iran or further east.