Buy a kit from one of the specialist suppliers, these fit straight on and have the right airflow requirements for the vehicle. Sensors fit straight onto the vehicle, and wiring is usually integrated.
This will be slightly more expensive than sourcing scrappers, and alleviate any problems with inadequate airflow, particularly when off roading in low box, and a radiator clogged with mud.
Newer fans will have two speeds, this is better for fuel consumption as the second stage, or speed only kicks in when necessary.
Over the years, i have spent hours fitting electric fans to engines and suffered all the problems, and experience has taught me to purchase a purpose made system.