DING, DING, DING. We have a winner here! I received my Champion N5C spark plug from Amazon today, took it up to my shop, screwed it into my original Offenhauser head, and it fits perfectly. The champion documentation says that the "N" series plugs have a 13/16" reach. which seems way to much, but as I said above, it fit perfectly. I didn't have my good camera with me today, so I had to take this picture with my old "Flip-Fone", but I think it shows the perfect fit.
I knew my old memories would be worth something! So you guys can forget milling machines, spacers, chamfering tools and all of that kind of stuff. Just get some Champion "N" series plugs (or their equivalents; there are a lot out there) and just screw them in.
