WHAT HAPPENED TO THE SATURN V PLANS
Despite a widespread belief to the contrary, the Saturn V blueprints have not been lost. They are kept at Marshall Space Flight Center on microfilm. The Federal Archives in East Point, GA also has 2900 cubic feet of Saturn documents. Rocketdyne has in its archives dozens of volumes from its Knowledge Retention Program. This effort was initiated in the late '60s to document every facet of F-1 and J-2 engine production to assist in any future re-start.
The problem in re-creating the Saturn V is not finding the drawings, it is finding vendors who can supply mid-1960's vintage hardware (like guidance system components), and the fact that the launch pads and VAB have been converted to Space Shuttle use, so you have no place to launch from.
By the time you redesign to accommodate available hardware and re-modify the launch pads, you may as well have started from scratch with a clean sheet design.