Where to buy a 727 transmission

I have replace the dowel pins and I am using the B/M heavy duty flexplate. The part of the converter that slides into the transmission is what I'm calling the snout.
The block started out as a 360 and was changed to a 408.
No line boring was done.
Tuesday the motor and tranny are going to be checked for alignment. If the transmission is junk I want to get a new one as fast as possible. Short car show season in Massachusetts. I have heard bad thing about TCI. Not sure how B/M transmission are.