I made serious headway into recreating the complete set of standard unix core utilities (excepting C compiler, et alii) in Perl,

Sounds much like the Unix Reconstruction Project. Last time I looked, I had the impression that the project was sleeping, and a random look in some of the code revealed stuff like ad hoc handling of cmd line switches, whereas one would reasonably use some Getopt::* module nowadays. I wanted to check just to be sure not to shout utter nonsense but the site seems unreachable today...