sccs2rcs is a script to convert an existing SCCS history into an RCS history without losing any of the information contained therein. It requires that the SCCS and RCS tools be installed on your system.
Run this in a directory with an SCCS subdirectory. It will convert all the SCCS files to corresponding RCS master files in a new RCS directory; the SCCS data itself is accessed read-only. It will complain and terminate if any of the SCCS files are checked out or if the RCS directory already exists and is nonempty. If the directory contains snapshot auxiliary data produced by Emacs VC mode for tagging, that will be used too.
Date, time, author, comments, and branches, are all preserved. Most SCCS keywords are translated to RCS keywords; it will complain about the exceptions so you can see them.
If this tool fails it will tell you why. `rm -rf RCS; unget SCCS/s.*' will recover your initial state.
There is one option. With -c you can specify an initial-comments file. Each line should consist of a filename followed by a colon, followed by the RCS initial coment to set for that file.