From the NASA-Marshall Space Flight Center, December, 1961: An illustration of the forthcoming Saturn C-5 S-IC stage. This appears to be *mostly* as the S-IC would be built, but there are some detectable differences. Missing are the four small (and apparently superfluous) stabilizing fins that appeared on the outboard engine fairings. And located at the front are the eight retro rockets that would end up inside the aforementioned engine fairings.
This illustration came via EBay. The full-resolution scan (all 15+ megabytes of it) is available in the 2016-12 Dropbox folder for APR patrons. If you’d like to gain access to this and two years worth of high-rez aerospace goodies like this, as well as help out the effort to procure and preserve aerospace goodies like this, please consider joining the APR Patreon.