Soviet Union, not Russia...Russia had a major problem in 1945-46.
It was the Western Allies that were supplying the fuel for the Western Lend Lease aircraft. It was also the Allies that were supplying a large part of the Tetra ethyl lead to allowed the Russian fuel to get into the 95 octane range. How much stuff they had stockpiled and how long it would last?
2nd problem is that it is only around 330-350 miles from Tehran to Baku. Given several months to deploy (like you would need to move a number of B-29s anywhere in the summer/fall of 1945) the Soviets were be facing heavy bombing from air bases in Iraq-Iran and given the amount of rail, road and barge infrastructure that that existed for the Lend Lease supply route/s building the bases would not be overly hard.
Russia had some very good scientists and engineers. They had a rather crappy/spotty infrastructure to supply certain materials in large quantities.
Good point about the fuel. VVS experienced a shortage of gasoline regularly in early 1945. The war against Japan required another effort and moving the stocks to the Far East.
Tehran is close to Baku but the Soviet Army was still in Iran in 1945. Allies can use other bases in the region, of course.