Wow! Just got back from the mountains and read the messages. Thanks for such considered responses and generous offers. (Shame on me for being blind sided by such unexpected kindness!).
I think replacing the frame with an older one will be perfect and provide a better long term solution than my home made sleeve repair. I am happy to pay shipping costs of course.
The broken frame I have is 235mm from the nose plate to the middle of the rear plate. "A 80" is stamped in the rear frame plate- probably for 1980 year of manufacture.
I'll send a private message to FBOATSB and take it from there.