I have a JR which is about the same as the six channel sport and it is easy to convert to mode 1, you change the set up to “mod 1” and move the spring and slider from left to right. When you have done that you simply swap the aileron and rudder servos at the receiver in the plane and you have mode 3. Then you have to use a buddy box just make sure they are both mode 1, so long as the servos are swapped at the receiver they will work in mode 3. Some JR radios can be changed in its setup to mode 3 but you still have to change the throttle setup to that of a mode 1 radio.
The problem with a radio what is converted to mode 3 by changing the wiring on the inside is that if you want to shell it later you got to have it changed again.