Folks, thanks for all the information and links you provided. This will keep me busy (in a good way) for at least the near-future. Thanks !
One last question though: I find it interesting that (early) SPARC/SunOS is not mentioned yet. Is the SPARC hardware not emulated (yet), or is the software simply not available ? I imagined that at least early SunOS, back when it was based on BSD instead of SYSV, would have been a likely target for emulation ?