This was prepared after Armstrong and Aldrin were already on the moon in the event they were unable to lift off:
https://www.archives.gov/files/presi...n100-6-1-2.pdf
There is a short out now on Vimeo that references some parts of the speech. I hadn’t know of the never given speech and found it an interesting sidelight.
The short is “Others Will Follow”. Easily googled.
Edit: Or link here.