for my opinion I would do something like this in my solution
solution.Model -- the model that reflects your db,
solution.Repository
solution.MVC -- your model will be the refined Model, referencing the solution.Model
solution.Test
solution.WebService -- referencing solution.Model
I keep my Model outside my MVC Web application and just put the refined ViewModels in my MVC Model folder. I don't know much about pro's and con's but this is just a better way of doing it for me.
Doing this, you can use your Model anyway you want. Maybe you want to use it for WebService as what you ask. Or for another Application. You just reference your Model project to other projects that you need them.