You have about a 10% chance of winning this one and then you will only have one infantry left. From what I have heard the axis only win about 5% of the time if you are playing without bids. So if victory is all you care about then go ahead. However, even if you do take it, there is a good chance that the allies could take it back.
The German airforce and navy was used to clear out the battleship and sub, which means that the Gibraltar battleship might have made it. Combined with the E. Canada transport and armor it gives the UK a slim chance at liberation.
If the they can’t do it then the US can send the bomber and two infantry. The bomber to clear the navy and the two infantry to attack the one German defender.
Then Russia can send their transport with two infantry and the sub and fighters to clear any navy.
The allies will probably be able to retake it, but it should not matter. Germany should have bought 10 infantry on G1 and saved 2. On G2 they can buy about 25 infantry with the money kindly provided by the UK. On G3 purchase 6 or 7 armor. So on G4 they can smash Russia in Karelia.
I would say if you are going to do this, just get the money, leave, go smash Russia.
However, all of this is provided that Russia is dumb enough not to move the tranport and sub on R1 and Germany gets extremely lucky when it invades the UK.