You'll need a lot more info than that. Best to have a commercial contractor run a heat load calculation for you. Restaurants have other factors to consider, such as make-up air for the kitchen, lighting, humidity loads from food prep, cleaning, etc. And the heat gain/loss from the structure itself.
Don't scrimp on this. Nothing sucks more than going to a restaurant that is poorly cooled or heated. I can tolerate a cool one but if the wife is cold the dining experience isn't pleasant. You know what they say about keeping mama happy...
Building Physics Rule #1: Hot flows to cold.
Building Physics Rule #2: Higher air pressure moves toward lower air pressure
Building Physics Rule #3: Higher moisture concentration moves toward lower moisture concentration.