the Standup Manufacturing Plant I says:
The Standup Manufacturing Plant I is a service module that allows manufacturing of any product (except Capital and Super Capital ships) when installed into an Upwell technology structure.
You can build Orca, freighters and jump freighters in a Standup manufacturing plant.
Bowhead is classified as a freighter and it has 3 medium, 3 low and 3 XL rig slots. Pity regular freighters don’t have the same fitting options - give pilots some interesting tradeoffs between speed, capacity and tank.
Freighters doesnt have rig slots, only lowslots and very limited powergrid and CPU, so you can basically only fit a couple of different modules on it.
You can manufacture these in highsec, freigher and jump freighter. The Orca isnt a capital, its a large boat, so its not really subject to manufacturing restrictions anyway.