Thought I would post a follow-up to this post. Thanks to "gmc-is-me" I worked with Grant Rings and Craig Marder there who spent time with me on the phone and through emails and helped me size a correct ring for this 270. Craig was a big help and walked me through the three measurements he needed.
To put this in context, this effort was for just one ring - to the tune of $11.45 including shipping. I told him I would purchase a complete set for a 270 with one additional oil ring to help make it a little more cost effective for Grant. When we finished - he billed me for one ring - and sent the request to their shop who made me a perfect fit oil ring set.
This was not a money maker for Grant Rings - and I don't know how often they receive work for these old engines; but I suspect that this special order required his patience...that he graciously assisted with to help me get on my way (or, out of his way... LOL).
Just FYI. More than pleased with the service, the connection, the good work and the help.
Tom
Last edited by tom moore; 10/14/2020 2:13 PM.