Easiest way I can think of is to rip the disc to an MKV file, then load that into mkvtoolnix and change the framerate in that to 23.976 and render out a new video-only MKV - this will only really work for the video, but it’ll actually change the frame rate the video file is played at, as opposed to Handbrake, which will try to interpolate (blend existing/create new) frames to preserve the speed and runtime of the original. Plus, mkvtoolnix won’t reencode the video, just change the frame rate flags.

Whether that will easily sync to the NTSC 4.1 once you have the file running at the right speed is a different story.

I think eac3to should be able to take the audio from your PAL video and convert it to NTSC speed (lowering the pitch to its correct…uh, pitch in the process), but I don’t know the command offhand for that and also don’t know if that’s available for Mac.