Then once you start working with them you discover that the tech and architecture are a reflection of their management structure, and then you find out they rea

Then once you start working with them you discover that the tech and architecture are a reflection of their management structure, and then you find out they really don't want a port/rebuild, they want a new product (but this only becomes apparent half way through the rebuild). Green field projects are much easier, but you really need to have a great product owner/manager. Tldr: It's not just coding, it's people.