Still looking for that TA ring - thanks to those who have replied with helpful suggestions...
Two things I forgot to mention: 1) I'm not picky about number of teeth - anything between 51 and 58 would be fine...
2) If you have some old TA rings lying around, and don't feel like measuring them to see if any are 1/8 inch, TA often (always?) stamped the 1/8 rings with a number "3", often under the stamped number designating the number of teeth on the ring...
Sheldon "TA" Brown, any chance you have one lying around?
Thanks again to all...
Duncan Granger
Mountville, PA