Back when I had my 240D with 300D na euro motor with the 307 diff and five speed the car would run 100 mph in either fourth or fifth.

(for what it is worth).

Where the taller gear helps is mpg which that car would do 40 mpg if driven 60 to 65 mph.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.