Thanks to the Wayback Machine, the old NASA KSC Next Gen sites from before and after 2017 are still available.
The older “pre-2017” site contains *many* documents deleted in 2017 after policy changes and resource limitations meant not every document could be transferred to the new website.
Yet here they are!
The KSC Next Gen Site (pre-2017)
Adding a couple more years of content, the updated KSC Next Gen site, also since deleted by NASA, is available here too.
The KSC Next Gen Site (post-2017)