Hello, my heads have excessive lower valve guide wear and will have to be replaced, the problem is that on one head, the ehhaust guide was missing it's retaining ring, ET122, someone had just smeared in some sort of epoxy as a replacement. After cleaning the threads from the epoxy it turns out that there is very little left in the way of threads for the ring. I am wondering what might be the best fix, make an oversized ring, run the guide without the retaining ring or some other fix. Thanks in advance.