Temp sensor location

The engine is a 1974 360.
After 40 minutes of "spirited" driving.

Autometer mechanical gauge in the water pump right next to the bypass hose reads 180 degrees.
FI Tech sensor in the intake manifold reads 200 degrees.
Cheap Craftsman heat gun reads 190 degrees when pointed at the top of the factory 22" radiator.

Is the water temp really that different at those locations, or are one or more of these sensors suspect?