Member of the San Francisco Game Group since 2005
This is a customized Bane Tower from the game Man o' War
Buried in another thread for SGoM:
The nominal scale of the plastic miniatures is 1:1200 (the metal minis from Richard Houston and GameTech were really closer to 1:1000). Since the game is long out of print it i getting harder to find extra plastic minis, but GDW used to sell separate boxes of the British and Martian ship sprues under their Adversaries miniatures lines.
At any rate, the scale of the game may not be what you expect (especially if you are familiar with Aeronef). SGoM is really based on small scale actions (one-on-one battles vs. fleet actions) so that is why there are a smaller number of ships (than you expected).