Are we arguing about different things, Dan? My grandma had a Rangoon Red '63 Galaxie XL convertible with a 390 Z-code/C6 and full-boat options, including PS and PB. I know because I sold it for her in 1986! Agree that you couldn't have gotten that car with a Q or R code and auto, but not sure if PS or PB would have been available with those motors ... ?Not on early cars like the 63, it wasn't until the C6 Auto trans came out that you could get HP motors with a auto trans. 1966 and that's the alphanumerical designation, C= the 60s decade 6=the year. So by the time Ford put out the 7 liter engine 66 Galaxy & GT/ GTA Fairlane's you could get it both in auto or 4speed. In 67 the mustangs got a bigger engine compartment and GT 390s with the C6 as well as the Fairlanes
As for me I would never put the early PS in a fast car as I want the solid feel of manual steering. But with a auto trans you can't rock the gears like a 4speed parking it with manual, so a 4speed also helps steering the car at slow speed. But I wouldn't want squirrely steering at 130mph