What are the Germans doing while you set all this up with the British? It does not sound like you are making a push into Southern Russia to contest the Germans which means by turn around turn 8 you’re going to be against a united Eurasia with Germany making 100+ IPCs. 30+ British IPCs in the Middle East does not stop 100+ IPCs worth of Germans coming through the Caucasus. In this scenario, the only way the British could hold onto the Middle East (and more importantly Cairo) is if the Americans are committing 100% of their resources on Western Europe but that can only happen if the Japanese have been contained to the Home Islands.
Holding the Middle East is important to the Allies for the sake of denying the Axis those IPCs but it is not a game winning position.
A gaming winning position is where:
The Japanese have been contained to the Home Islands,
The British hold the Middle East,
The Allies are beating/stalmating Germany in economics because of SBRs and convoy disruptions,
The Allies are threatening landings all over Western Europe from Gibraltar