[HELP] "Real" PAL<>NTSC framerate conversion with speed changing?

[Selur]

I'm not sure we're on the same page. I don't want a speed-change. I want to convert PAL to NTSC and vice versa in a way it will cause the video to change in speed, as more or less frames should be played in 1 second. I don't want to affect the total number of frames.
...
Keep all frames, making the clip like 4.3% (I think) longer.

It's the second thing I'm looking for.

this is done by changing how many frames are shown during a second -> so a speed change
By changing the playback speed (= the time each frame is shown) the frame count isn't changed and thus the total playback length changes.

There might be more decimals after it.

"23.976" is internally converted to 24000/1001.

I have to admit these terms go beyond my knowledge of video encoding (if that's the right word even).

cfr = constant frame rate (usually anything that is broadcasted or from a physical media)
vfr = variable frame rate (mobile camera captures and some anime encodes from scene groups)

Cu Selur