Classic/Antique Car Repair: Vehicle overheating, dominator manifold, street dominator

Question
my 65 Corvette has a big problem with overheating. I've even installed an electric fan on the radiator to act as a supplement. 327 cu in.  4160 holly carb,  Street dominator manifold and headers. Jim

Answer
I am not a corvette guy, so I don't know much about your car. I do know that most older cars have plugged radiators, and that is probably your problem.  You can't just flow a rad. and say it is clear.  I say rod them out and make sure.  Your car was engineered to run cool with the standard fan.  The only thing and electric fan will do is help out at idle and parade runs.  If you  have a lot more engine now than when the car was built, then you probably need a higher capacity rad.  Look into that.  Bigger engine means more heat rejection.
Other things that can cause overheating is a blown or loose head gasket.  If the combustion products get into the water jacket, then you are sure to overheat, even on a cool day.  Torque down that head to the specs.
Check you engine timing, that can cause it.
A loose impeller on the water pump can cause it also.  
I bet it is the rad.  Make sure it is large enough for you power plant, then have it rodded out.
Join a vette car club and let them help you.
Good luck with your car.
jack