I would be tempted to take one of those monitor extension cords (...) and wire it to the pins with some heat shrink.
Eek!
As the orignal connector doesn't look very safe by today's standards, my advice will be [dave's voice] Don't plug it in, take it apart! [/dave's voice] and solder in a proper IEC chassis. Costs pennies (or nothing if ripped out of an old PC) and it's much
safer than any other (hap)hazard way.