For straight engine swaps that you are retaining your current ECU, to avoid introducing any uncertainty, it is best to retain the old package of sensors that you know are good and are able to start the engine.
Chances are the sensors on the new engine will probably work - keep them as spares, but always consider the car this engine came from was broken up for a reason.
Do you have any history of the new engines servicing? - This is the perfect time to replace timing belt and water pump.