You have come across the one dead end I have in my Wilbur line.You and I must be distantly related.I have considerable information on the Wilburs/Wilbors/Wilbers from whom Lemuel descends.He and Sarah Fisher appear to have "removed" to Stafford, Connecticut just south of Sturbridge,Massachusetts.
Most all of our common Wilbur ancestors are buried (as you undoubtedly know) in the Pleasant Street Cemetery in Raynham Center, Massachusetts.
I did find THIS Lemuel Wilbur's grave in an ancient cemetery in Stafford, CT.but Sarah is NOT buried with him and his gravestone (died 26 May 1819) stands alone toward the front corner of the old burial ground on a country road.
The name "Bradford" is used and re-used in this branch of my family yet I cannot find a concrete genealogical connection to the obvious "Bradford" (or any 'Bradford' for that matter).I wish I could be of more help but Sarah Fisher Wilbur remains an enigma.
Some accounts have her born in Bridgewater,Massachusetts in 1723 OR 1743 and others Dedham,Massachusetts.Let me know if you have found anything new.