You know, not to be a contrarian for the sake of being a contrarian, but there's value in this project by itself. Being so attached to a contractual payment is some weird petiness if you really think about it. And counterintuitively that probably holds you back in many ways, in real life.
The sole connection to a person of such authority is, in itself, a so-called reward, growing it further is the cherry on top. Add to that the possibility of expanding your experience, your know-how, the little connections with many other artisans, being exposed to many other types of work and how it all works together... People these days don't take building up a resume very seriously it seems.
Not to mention how his name is bound to spread, although this is often countered by the lame dimwit authors writing their characters to be wusses afraid of fame for whatever weak reason. But in a medieval settings, it's an artisan lifeline for real.
All of that, and many other little things you'd be bored to read about, is what defines the 'opportunity' this project is. And just this opportunity to work on it is a reward that dwarfs any monetary gains. Easily.
