Both Super8 cameras and projectors often have a choice of 18 or 24 fps.
Please don't do an irregular pulldown. Please do what Karyudo said (encode at 23.976 fps). Please don't do what Karyudo said later (take frame-length chunks of audio out here and there).
24 fps is not 23.976 fps but 23.976 fps is 23.98 fps.