It looks like you'll have your work cut out for you--but the results should be worth it. Don't sweat it over the BW35. If it's rebuilt and performs properly it will suit the car well and last a long time. I've owned a 4 speed '70, an OD '72 and an auto '73. My own personal opinion is that the auto is more in keeping with the nature of the car. They handle well enough but the extra wheelbase and front end weight make themselves known if pushed hard. The 3.31 rear gears keep the rpm at a reasonable level for cruising and a 164 will never be a mpg champ but you can enjoy it for what it is. BTW-early (my wife's '76) 240's had a vacuum pump mounted on the cam cover.