Aha! I've been waiting for the first station... And I need an Alamo for my Starbase defences!
Looks good.
Basing size on dimensions is IMO a bit irrelevant - I've been looking at general impression of size and just going with gut instinct. But size 9 or 10 would be about right.
One criticism: why do you need drive systems at all? Impulse might make sense, as it may need to move under its own power, but warp drive is completely irrelevant. Unlike the FASA system, you do not to provide explicit power to your weapon systems.
I think you can just assume the relevant power generators are part of the general structure. Use the spare space to upgrade your structure or harden key systems or enhance shielding - a battlestation is TOUGH! I might upgrade the various secondary systems too.
Kudos on being the first station designer though
Jon
"There are worlds out there where the sky is burning, where the sea is asleep and the rivers dream; people made of smoke and cities made of song.
Somewhere there's danger, somewhere there's injustice, and somewhere else the tea is getting cold. Come on, Ace, we've got work to do."
THE DOCTOR, "Survival" (Doctor Who)