Did it overheat before doing the work on it? If not, then maybe the new thermostat is the wrong type, too high temperature, or faulty? The opening temp should be 82deg C (fully open at 90deg).
Doubt its the water pump, although I did have a 140 with a cast iron impeller pump where the blades of the impeller had rotted completely away. The coolant flow was dismal, basically reduced to not much more than the thermo syphon effect of the cooling system.
If the top radiator hose gets hot as the engine warms up to normal operating temp, you can probably discount any problems with the pump or thermostat.
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Steve.