Based on the photo on page 6 of the manual, changing receivers should be very simple.
http://www.horizonhobby.com/ProdInfo...PTS_Lo-Res.pdf
Remove the screw that holds what looks like a plywood tray in front of the servos and unwrap the receiver from its foam padding.

I am guessing about the receiver antenna, but I would think it runs through a tube and exits near the rear of the fuselage. If so, tie a strong thread to the end of the antenna wire, before you pull it through the tube, so you’ll have an easy way to pull the new antenna wire through.

The JR servos and switch wire will plug into almost any “modern” receiver.