Your last post makes no sense, Mopar has used two different diameter bolt circles on 727 converters, 10" and 11". The original '66 would have used the 11" bolt circle, if you got a flexplate with the 10" bolt circle it obviously wouldn't work, all you needed to do was get a flexplate for the 11" bolt circle. Sending the converter back to have the drive lugs moved was an unneccessary expense, TCI should have advised you to that.

A change in the thread size of the drive lugs shouldn't necessitate a "shim kit", sounds like TCI screwed you all around.