Are you saying the film should be slowed to 40% of the original value or the playback speed when put into modern video software should be reduced from 100% playback speed to 60% playback speed?
Are you new to MLH theory? If so, I'll explain a few concepts.
To Simulate Lunar gravity EXACTLY, we only need to slow the frame rate to 40%. (meaning a 60% slowdown, a factor of 2.5x)... 2.5^2= 6.25... which is nearly the ratio of Earth to Moon gravity.
However, the slowdown was almost NEVER 40%... but only for cases where objects were thrown/dropped on purpose... such as the hammer/feather.... and the SEQ tape pendulum (although here it looks like they may have only done 50%, ooops).
The other way to simulate lunar gravity is "wire suspension", to slow their fall, and increase their rise height. The MLH theory posits that it was USUALLY A MIX between the two. Because it's really awkward to truly only be 1/6th your weight.... instead they would split the difference, such as lifting only 50% of your weight, and then slowing the camera to about 60% -- combined -- these two simulate (well enough) lunar gravity.. (some slow motion coupled with some lift)
If you want me to go into more detail, please message me on this forum, or friend request me on FB. You seem like someone with whom I'd like to have more conversation. Not that I'd expect you to agree with my conclusions, but that our conversation would probably be fruitful. You seem smart, courteous, considerate and genuine.