I almost bought a 69 Polara 500 convertible the other day with a factory 383 3-speed on the tree! One of the stoutest cars I have ever driven on the street was a 70 Duster 340 with 3-speed floor shift and 3.91 gears, it was tough to beat!
The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.
One of the stoutest cars I have ever driven on the street was a 70 Duster 340 with 3-speed floor shift and 3.91 gears, it was tough to beat! 
