FCP is almost 99% of time actually editing in 23.976fps, not 24
Sound people, however, are almost always at 24.
Have your sound editor coform their mix in a 29.97 fps project, and export those files to you. 29.97 and 23.98 are essentially the same as far as audio is concerned.
when you get a film print done, the Dolby technician should be made aware of the speed your audio gear is running at, and they’ll correct for the percentage on the MO disc.