This is a relatively simple change. You will need to swap the MOS 6567 for a 6569 at U23 to go from NTSC to PAL. You need to open the link at LK5 and close the link at LK4. Finally swap the crystal at Y1 for the 17MHz one. To go from PAL to NTSC you need to swap the MOS 6569 for a 6567, close LK5, open LK4, and swap the crystal at Y1 for the 14.31818MHz one. Lastly make the color adjustment with the small trimmer until you get good color. Make the adjusments VERY SLOWLY with a non-metallic tool.