Both of the things that you mentioned, either a bad battery or its flat due to a dodgy alternator, carb issues or maybe its just not sparking for some reason - plugs, ht leads, dizzy cap, rotor arm, coil.
I would start by trying to jump start it, then check spark at the plugs, then if you still havn't sorted it move onto air filter and carb. There is a good post on setting up Pierburg carbs in the 'Maintenance and Info' child board on this part of the forum.
