Bring back the Saturn V!
I read they have the technical specs but don’t have the ability to rebuild the actual Saturn V as was built during the Apollo program. There were so many intricate welds and tweaks that were never written down.
I did read where a company took the specs for the Saturn V and said they could produce close to it using old technology but that using some new technology with old could produce a stronger version of the Saturn V and substantially cheaper than the current SLS boondoggle.