FCP can work at PAL, NSTC and HD frame rates and pixel aspects. Your monitors and I/O cards (no specific hardware mentioned but I will assume you have something), need to be PAL/ NTSC auto switchable.
If ingesting from digi beta and playing out to digi beta, you will need to hire in an NSTC deck. Sony decks can playback NTSC depending on the model and the options but dual record in digi beta is not possible as far as I know. The humble J3 playback deck can be switched to NSTC or PAL playback.
The other catch is reference video needs to be switched to NTSC if you have a proper referenced edit setup which I would expect with a facility that captures and plays out to digi beta. Do you have a switchable reference video generator?