So here are some pictures of the inside of the phone and electrical. The bells appears to be connected as you can see that one dangling wire, but that shouldn't be a problem since I'm gutting it anyway. The one thing I do not know is if I can get the bells to actually ring. That will be a large adventure in itself since it will require a lot of electricity. I plan on making the phone without the bells for the moment, maybe add them on later.
I will take a look into that box on the left of the phone when I gut the phone so we can see how it works. It seems to mark which wire is what, but I can't tell you anything about what those letters corresponds to.