Boy, does this question open up a can of worms!
Some things it could be that I can think of.....
Timing off (too much)
Bad Thermostat or Tstat installed incorrectly.
blocked water passages in engine.
Head gasket
air in the cooling system
bad water pump or wrong pump (one for a clockwise rotation engine used)
Blocked radiator
That is all I can think of for now. Just because new parts may have been used doesn't mean that they could not be bad!
Timing off (too much)
Bad Thermostat or Tstat installed incorrectly.
blocked water passages in engine.
Head gasket
air in the cooling system
bad water pump or wrong pump (one for a clockwise rotation engine used)
Blocked radiator
That is all I can think of for now. Just because new parts may have been used doesn't mean that they could not be bad!