Making a flash-sync adapter for sx-70?

I know they make adapters for the sx-70 that'll allow the use of an external flash. I'd rather make my own. The plug I've seen is the same shape as the flash bar plug shown in my pic below. I've dismantled the flash bar and cut off the bulbs and excess metal. If I take a sync cable and strip the ends off, which nodes do I solder them to on the flash bar plug? This is possible, right?

It is possible but not in the way you describe. An adapter will be needed. See this article for more information on flashbars and instructions on how to build your own adapter.