I have installed several over the years. A pusher or draw through will work well. I have used the stock Volvo sensor in the rad. Most of the aftermarket rads have this hole for the grommet, which then accepts the push-fit sensor capsule. A Bosch relay is then wired to the sensor, which in turn handles the current to the fan. The underhose type sensors, used by some of the fan manufactuers, is a bit less elegant. I have not used them.
With the electric fan you can dispense with the big shroud, which is exactly what Volvo did on the 940 series with electric fans. You will notice a difference in mileage and noise.