You might wanna stick with the valve cover gasket kit, Unless you feel confident getting the plug seals dead on. They need a wedge in order to grab the cover properly, to keep oil out of your plug wires.
As far as the bolts are concerned, other 323 forums just say to use any old bolt as long as you keep the torque low and proper. Chrome bolts like that should be fairly easy to come by, either a hardware store, or measure them up and look online. Or if you're lucky to have a pull yard nearby there's plenty of cars with the b6 engine that have the same bolts.