The CR, TL, came in 271 hp, 289's and 427 Galaxies, both by 1964. I had 2 of them in, '64 271 hp Fairlane and a 65 1/2 Mustang, both small shafts, that also, includes the cluster shaft.
The CR was designed to be usable for race applications, with narrow power bands. In that regard, you gear for max mph you need, at your desired rpm and it has progressively less, rpm drops i. e. For a 7k engine, 1-2 ~1900, 2-3 ~1700, 3-4 ~1600. That keeps you higher in the power band, as speed increases. You can have wider spits and lower speeds, as the you have more tq multiplication, in lower gears and then, you need your higher power band, with less gear and more wind resistance.
The WR was a more streetable transmission, usually used in lower hp engines and is also progressive. For 7k it's, 1-2 ~2100, 2-3 ~2200, 3-4 ~1900 rpm. With more modern, lower rpm, wide torque band, 450+ ci engines, I can see where it would be useful but, for the HiPo cars of the day (7k+ 289 & 427), the WR wouldn't cut it.
Today, the 5 & 6 speeds are what are best for the street. Low cruise rpm and lots of gear reduction.