I need to do some archeology and get the source of perl 1.0. Preferably modified to compile on a modern platform.

That's all part of the official Perl repository at https://github.com/Perl/perl5/commits/maint-1.0.

Update: See also https://www.nntp.perl.org/group/perl.perl1.porters/ and Perl 1.0.15 released on P5P.