You mention Fats and you're stance is similar.
If your chin is on the cue to maybe 12-18" above, the goal is a right angle with the upper arm and forearm. Distances from the cue depends on how tall you are, but if you're standing totally erect, the 90deg thing has to go out the window I think. In this extreme case the stroke comes from the shoulder. The forearm is stationary.
I'm not an instructor. Only try to study this kind of stuff.
Many years ago my instructor forced me to stand taller so I can see the angles better. Since he passed away years ago I've migrated closer to the cue, but not snooker style. Yet.
He also taught that a billiard stroke was more of an "Arm Stroke" than for pool.
That may be because he stood taller and the taller you get, the more the shoulder/elbow has to comes into play. (never thought of this till now)
I think you sort of asked, how do I know where I'm stroking the CB. That's the rub. The further away you are from the CB the harder is is to see much less hit where you want. Parallax its called. That part simply takes practice.
There's been a lot of great players that stood tall. It's not right, wrong or proof of anything except, excelling at the game can be done with any distance from the CB.