Is this as it goes down the road at some speed, or when it's stopped, or running slowly (ie in traffic)?
Does it have the stock pulleys driving the water pump?
Are you sure your temp gauge is reading right?
Is it possible some of the tubes in the radiator are clogged (is the radiator orriginal to the car)?
The other suggestions are good too.
Without further info on your combo though it's difficult to tell.
I would run a 185* T'stat in that, as you say it's carbbed, but that's me.