Brando's GMT was a model 1675 which he got in the 70s and wore when he was making Apocalypse Now. The 16750 came out around 1978 or so with the 3075 movement and is a later watch. GMT Master IIs came out after that in the 80s.
As has been mentioned, you could buy a cartel 1675 from a TD like Marvellous and see if removing the bezel and insert would leave you with a a crystal retention ring- giving you the Brando look.
A 2836 with the GMT hand might be a little more reliable than a DG3804, butI I've had good luck with my 3804 movement.
This Pan Am 1675 has gen bezel construction- it's a modified 1655 with a Clark's bezel assembly, T-116 and a Ingod44 white Pan Am dial.
8-10 years ago people were taking the cartel 1655 Explorers and making 1675s out of them- it required some case shaping and a bezel assembly from Clark's, but you ended up with a nice 1675.