Maybe it is something like this the OP had in mind.
G1: Major
G2: Carrier, destroyer, 5 transports
G3: Put 10 units in Caucasus
G4: Repeat
Well. First of all a major, carrier, destroyer and 5 transports is 89 IPC. Initially it seems very attractive to do this and I will try at some point. Securing caucasus, middleast and volgograd (probably) by G5 seems very tempting even at this crazy cost
Extra income
G3 + 7 for caucasus, Soviet -2 (9 difference)
G4 + 14 for caucasus and volgograd + 2 for NW Persia and -4 for Soviet (20 difference)
G5 You might even have iraq and Persia as well
You open a two front war with Soviet. Difficult with only slow moving inf/art for Soviet. Also difficult for allies to reinforce the middle east. So at this great cost there are also huge advatages. At least looks like it at first.
But here is the catch. I think it is impossible to defend this black sea fleet long term. You build 10 bombers with USA and blow it up. Even the UK might be able to blow it up by UK 5 or 6.