I'd like to make this vegetarian. what quantity of beans/mushrooms/etc. would you suggest for a meat substitute?

I just tested this chili recipe for community pick: http://food52.com/recipes/15605_white_bean_and_quinoa_chili
I had been looking for (and trying to develop myself) a good vegetarian chili, and I thought the combination of quinoa and beans was an excellent substitute for meat. To keep the same proportions as in Chrissy's chili, I'd use a cup of quinoa and 4 cups of beans. I hope this works for you.