Go4zgate2.0.tar.gz is broken. The real archive should look like this:

ftp/pub/network/gopher/Unix/gopher-gateways/go4zgate:
total 1054
-rw-r--r--   1 root     wheel      538710 Apr 26  1994 Go4zgate1.0.tar.Z
-rw-r--r--   1 root     wheel      531253 Jun 15  1995 Go4zgate2.0.tar.Z
-rw-r--r--   1 root     wheel         205 Jun 15  1995 Readme