First i've heard of it but i aint no honda historian.
"HERE":http://www.mopedarmy.com/photos/brand/22/1202/ is a '79 in the Photos section with the square headlight ... missing front fender so i dunno if it was modified or what. Missing the front fork horn-cover plastic too..
But this page about HONDA mopeds , PA50, etc. shows none with that style.
Headlights are prone to burn out and are expensive to replace .. so if the entire housing were replaced with one from some other bike (maybe an Elite or Express) the ignition switch might be left out.. Maybe the fork headset was replaced, including the bars.. so no kill switch?
Here's a '78 WIRING diagram ..