Well, I don't know about converting recipes, but here is an existing recipe for chocolate cake from the Celiac website:
One-Bowl Flourless Chocolate Cake (Gluten-Free)
I was thinking that if you found a similar one bowl chocolate cake recipe you could compare them and determine what you have to modify to make it celiac friendly.
IE don't use the recipe I post, but use it as a guideline for how to modify a standard chocolate cake recipe.
Otherwise, browse their website and see if they have the answers to your questions about what has to be replaced and how to calculate yield. Somehow I think there is bound to be a trial and error part to all this...