Well, they don't have nutritional information on their website.
The web site doesn't give a very good description of what it is either.
The only thing I could tell you is to break down all parts of that super spud and use the points guide to give you a general idea.
How big was the potato? A small potato (baked) is 2 points. If by eyeballing it the potato could have been maybe 3-4 small potatoes?
How many ounces of brisket?
What were the other ingredients? Cheese sauce? BBQ Sauce?
Butter on it?
The other option for you is to request nutritional information from the restaurant itself. Since it is a chain, they should have that info available to you upon request.