Rather than pure augmented production, try reducing the build costs of Space Yards.
If you increase the build rate too much, and a BC is done in one turn, it would be a major disincentive to build smaller ships.
If you reduce the price of SpaceYards, then players can rapidly get lots of orbital factory bases, perhaps 32 in the first 5 turns if they are cheap enough to self-replicate in one turn.
Players could then pump out either tons of small ships, a lot of medium ships or many large ships. A mixture of types would likely be best.
Variety is good.
