This is sooooo much easier with Atari 8-bits, or at least taking an NTSC one to PAL is. All you gotta do is replace the Antic chip with a PAL one. I'm sure that works both ways, though....
I've NO idea why anyone would want to go from PAL to NTSC considering that 99% of the software is PAL. Hence the reason I bought a PAL Amiga even though I live in the land that was previously known as America.