Beautiful space! I love the idea!
I think it depends on what your target market is... if you're looking to appeal to the masses, you'll likely need a few ingredients that can rotate based on season or "specials". If you're looking for the purist, two pies is doable, but only if you have transcendental pies and can build a die hard following.
Mind if I ask what price point you're thinking about setting your marinara and margherita at? I'm always curious...
Looking forward to more pics!