Louis, I could be wrong but I believe John Cope also provided the transmission and shipped it over 1000 miles so it wasn't just a $80 rebuild. A few yrs. back I nearly moved to take a job with John due to his knowledge and work ethic but then I screwed up my back and couldn't.
Since the OP took out a trashed trans I wonder if he properly flushed the cooler and lines? Maybe he didn't even know it needed to be done? As you know if their full of crap from the last trans it goes right into the new trans. Same for the converter. Did the old converter get reused without having it taken apart and cleaned? There are several possibilities.