What you are looking for is Pinch Weld Molding or Welt, you may find something close but when I was looking everything I found was a little bit smaller.
...and just for fun, Chrysler called it "weathercord".
I ended up ordering the Fairchild stuff from RockAuto. It looks pretty close to what's on my '69 than the eBay stuff, and hopefully I can call it close enough. I'll put up some pictures when I get it, compared to the existing stuff I have for both the '68 and '69.