now this is making sense........
Transmission shops (not all) will use the term HEMI to try and impress you with the word and charge you accordingly. Your corner transmission shops typically have little knowledge on performance converters. The HEMI converter is kind of a rare bird, and a converter rebuilder will ask for you to send in the core for rebuild, as they're hard to find.
The pilot size (or snout) are all the same size on a later 727. The converter hub has been the same size since 1962.