I realise this lens is basic and old but the rangefinder cam works with it! This is important to me. I'm 99% sure I'll never get a modern flash working with this but I thought I would check first
Sure, you'll need a cord for it or an adapter for that bi post sync. That's the two identical posts next to each other. You can make on yourself or buy one.
Super Graphic. Nice camera. I remember a pal of mine bought one when they were brand new and used an electronic flash with it. Some newer cameras can't take the "hot" voltage from older flash units but I never heard of it being a problem the other way around. If you look around you can find old Honeywell "potato masher" electronic flashes which are mounted on a tube and fit well alongside a Graphic. Have fun.
If you are able to solder a cable together, the bi-post is close enough to the pitch of a standard 0.2 pitch 2 way printed circuit board screw terminal.
Here is such a cable on the Graflite I modified to contain an electronic flash.
I intend to replace the tape around the soldered joints with a little cast block of epoxy.