Couldn't find exact details for you; but helped Project Manage a Richmond 6-Speed install into a '80 TA behind a '71 455 HO and can't remember what the 3rd member gearing was...but basically was a parroting of a '80s HPP '79 TA build called "Six Shooter" w same drivetrain.
Drove the car and can tell you passed 5 to 6 cars like was on a Sportbike...
FWIW - The mods to car were minimal, IIRC 2 holes cut into subframe (to relocate trans mount) minor Trans tunnel massage with rubber mallot & hammer...turned out a really nice balanced vehicle.
IIRC - Car was supposed to be painted Brewster Green but ended up w paint code 26(?) Metallic Blue w a Green tint? Was a real nice ride...