It was the ring.

I took out the FB ring and installed the old one into the new cylinder. It fired right up with all kinds of compression and not a single nastly clicking sound to be heard of!

Here's the video of me firing it up from having it completely torn apart tonight - cold start, first try. Sorry the video is dark, it was dark outsite but you get the point.

Frank is a good guy, he said he'd send me another ring to try.
(these videos are not public btw, you can only view them if you have a link like this one)

[youtube]http://www.youtube.com/watch?v=V6F5QFUjqLk[/youtube]