I agree that buying a package is a good plane.

But, assuming you already have the TX...

As mentioned above, use a Hitec crystal in the Hitec RX.

For the RX, if you want to switch brands in future, get one of the models that is "shift selectable". Some Hitec (and other brand) RX's have a switch or jumper, or automatically detect the shift of the transmitter. So you could use it with any FM TX on your channel.