Better might be an extended research tree for space yards.
However, if you want to build faster without having to edit anything, try a retrofit series.
Start with the minimum components, and build that. Then retrofit a few more components onto it each turn (while the SY builds more ships)
A Battlemoon in P&N would take about that much time, and is meant to. You can reduce the build time to 20 turns or so by using retrofits, emergency build, and huge-population SY worlds.
The key thing to note is that you can't have your whole army build from these huge ships. Settle for one or two as flagships, surrounded by a fleet of disposable baseships as cannon fodder
