Where are the .py files concerning health and happiness?

[roidesfoux]

I'd like it if there was a benefit to having excess health and happiness. One thing I thought of is making it so that if healthy - unhealthy is positive you get that much food (with a cap of the city's population). If happy - unhappy is positive, you get that much extra commerce (again with a cap of the city's population).
I don't really know Python, but I figured I'd give it a try before asking someone else to do it (although if anyone wants to take a shot at this, they're welcome to it). Does anyone know which files I want to look at?
Also, does anyone have any thoughts about what other benefits might be good/more balanced?

-RdF