I had 4 Tier 1, 3 tier 2 and 3 tier 3 factories for the standard goods, all maxed out. That is level 27 for tier 1 and 2, 23 for tier 3 (the upgrade to level 27 is researched early in chapter 14). Then I had 2 tier 1 sentient and 1 tier 2 sentient goods factories, also maxed at level 27. You do need at least one of each tier sentient goods factories, 2 is nice if your seeds production permits it. Of course, build only boosted factories.
I have always maintained 8 maxed workshops, all of those are magic by now, but you can manage with non magic ones as well. If you have a leveled Prosperity Towers you will need even less. Residences just enough to manage. About 20, I think, some of those magical and all maxed out.
Be aware that the guest race buildings of this chapter act like a set building. The more different connections each of the production buildings has, the better it performs.