Here’s the way I believe the work-flow would run:
1. Rip the PAL DVD to a PAL QuickTime clip with DVDxDV.com [not free, but great] or MPEG-streamclip [free, also good].
2. Bring the PAL QT clip into FCP.
3. Use Nattress Standards Converter to convert the clip to NTSC [see Nattress.com for instructions]
4. Import your new NTSC clip into your DVD program, and burn it as an NTSC DVD.
5. Grab a cup of coffee.
6. Enjoy.
I hope this helps.
All the best,
Wayne