Electric fan???

Shop manual will show if the factory thought it needed one.
They help mostly when the car is not moving - which these days is when we're stuck in traffic. :(
A shroud for '72 shouldn't be that difficult to find and mount. It's the pre-70 shrouds that are somewhat rare (but now reproduced).

To your original question.
Electrics are not usually as good as mechanical in terms of airflow.
More important IMO, adding an electric load to these cars, especially something like a fan that will be running at idle, really requires some modifications to the original wiring strategy.