Thanks again for all of the input. I went with the NOS set on ebay since they were a reasonable price. I hadn't really seen wear on the retainers before either, but then again I hadn't really been looking. So when I went to reassemble my head, I was about half done when I noticed one was so thin it looked like the edge could break off with a little force. I went back and checked them all and saw that the retaining flange varied a lot. Out of the 12 at least 5 had some noticeable wear.
