I very much doubt if this is possible..
I believe that the signal sent to the KN6500 screen is not in the same format as that required to connect directly to a TV Monitor or even a computer Monitor. The KN7000 has an additional integrated circuit on the PCB, which converts the signal being sent to the
KN7000's Digital Display, to one of two 'TV' standards : NTSC for USA TV and PAL for European/UK TV.
The option of NTSC/PAL output, is user selectable within the KN7000 operating system, as I'm sure you are aware, from your considerable experience with the KN7000.....
Since the KN6500 does not include this particular IC, then there will be no compatible signal to use to transfer to an external monitor.
If your question is related to a user who possibly has difficulty reading the small characters (Poor Vision ?) or maybe to show the screen in a larger format for demonstration/tuition, then a possible solution would be to use a video camera to 'Look' at the screen and connect its output to a compatible TV / Video Monitor....
Not very elegant... but may produce usable results.