Bombay forts: plans and photos sought

After visiting Bombay / Mumbai in 2017 a good friend is compiling an article on the Imperial era fortifications of Bombay, where the threat came from the sea. The records available at the India Office Records at the British Library and the National Archives are being accessed.

Would anyone here have pointers to or possess plans and photos from the WW2 era or any other time?

I have already pointed him to the only other relevant thread identified yesterday: Coast Artillery Units in India December 1941

Two of the sea forts, Middle Ground and Oyster Rock are shown below. The range finder towers were a later addition and to service the twin six-pounder guns, even if they finally were installed after the war ended in 1946.