W O Boz a 27.2 radius would mean you have a 54.4 diameter post..

Option, a 27,4 seat post then reaming the seat tube to make it fit can be done ... adjustable reamer , when I last checked, was a bit less than $100.

my LBS had one , I used it to put a 27.2 post, in a reamed 27.0 frame..





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