J-2S was consider as Space Shuttle main Engines (four in Orbiter) in early 1970s as Two way R&D program to start Shuttle with J-2S and Replace them with High Pressure Engines laterso Rocketdyne keeps the J-2 production on standby for NASA until they took SSME
RS-27A uses a larger thrust chamber than RS-27 that is more efficient in vacuum. It may be fair to say that it was derived from H-1/RS-27, but it was a new engine that did not use any parts scrounged from the old H-1 engines.
NASA (Langley, later Goddard) also had Scout, which averaged three launches per year during the 1970s and kept flying until 1994. Titan 3E was a NASA launch vehicle, developed only for the Agency (essentially a Titan 3D with a Centaur upper stage, a unique shroud, and other changes). It flew seven times.
Propellant tanks for S-IB-15 and S-IB-16 were manufactured and stored at Michoud, but were never assembled into stages. There are photos of these tanks in Lawrie's excellent book.
The procurement of long leadtime components for four additional Saturn IB Launch Vehicles (SA-213 through SA-216) was approved in August 1966. This approval was granted to retain the option to continue uninterrupted production of the Saturn IB Launch Vehicle if the requirement for additional launch vehicles became firm. The procurement of these additional launch vehicles (SA-213 through SA-216) was approved by Mr. Webb, NASA Administrator, on January 18, 1968. follow-on Saturn IB Launch Vehicles. Some long leadtime components such as tanks, structures, etc., have already been fabricated for vehicles 213 through 216. Steps are being taken to reorient the production and support activities to give the most economically sound program feasible that will result in qualified, flightworthy launch vehicles.