If your overheating going down the road at a speed over 30-40 mph you have air flow problems. IMO the fan does little cooling after 30 mph. I would adjust the timing, make sure you have all filler panels installed, and check the water pump to spacer plate for the correct clearance.
Here is a link.
http://www.wallaceracing.com/water-pump-mods.php
Let the car warm up with the radiator cap off, look for little bubbles in the cooling system. If you see a lot of bubbles you more than likely have a head gasket problem. Check your oil to make sure it is not milky looking.
You could also have a sticky thermostat. Changing one out to a lower temp will help the cooling system open and close at a lower temp. If you not driving the car in the winter this should not be a problem at all.
The fan also looks a little small for the car but seems to be sitting in the shroud in the right location.