The mechanical fan system should be more than capable of cooling a mostly stock 318 as long as the cooling system is in good repair and the engine is tuned well.
Since the OP’s temperatures seem to be getting high, and we know he’s already running a fan shroud and presumably has the hood seals, the radiator has probably just lost some efficiency with age/sediment/corrosion. He said it’s an AC car, so if the pulley is stock he should already have the overdriven water pump as well, although that’s worth checking.
The other thing is, if it isn’t getting hotter than 210* then there really isn’t an issue. Certainly not a big one.
If the radiator hasn’t been flushed or the coolant changes recently that would be a good step too.