So here is that shirt live:
@leftofthedial recommended size medium, which worked out nicely for me. Shoulders are right and sleeve length is good. Body is a moderately full cut without darts. I like the length. Quite long actually. Great for tucking and will work for me untucked in a sort of flowing way I think. I'll wear it untucked certainly.
Linen fabric is terrific. Light and crisp and after a cold wash and hang dry surprisingly unwrinkled.
Also, there's that...