Some Google+ contacts dont have a profile image, but they do have one in "Google Contacts". I think it would make sense if the fallback for those Google+ contacts where their "Google Contacts" profile image.
Is there a way to do this?
I think Google+ profile pictures have to be chosen by the people themselves. Your Google contacts are private to you while their profile picture on their public profile is public.
In their profile information you will see private contact data as well, but it's explicitly mentioned and are additional.
I don't think their is a way to do so because it just isn't meant to be done.