JS
the photo of Dick Mann only tells part of the story. You yourself will probably recall the quality of the tyres back then, compared to those currently used by MotoGP teams. Had Dick Mann had tyres like the present day ones, he would have cornered with the present day best. Put tyres with that old rubber on the modern bikes and see just how far the likes of Rossi and the others can lean over before the tyres let go.
Re comments on how to ride and similar, I doubt many riders conform to any kind of pattern with their riding techniques. Certainly during my years being involved with road racing , and working with champions, both World and National, I can say they were the most different in everything they did relative to their racing, all did it their own way.
Regarding leaning off and dragging knees on the ground, years ago a Rhodesian rider, Ray Amm, when racing works Nortons, would often move his body on top of the machine in a corner, rather than going in the same direction as the angle of bank. He got results, the method worked for him, but he was the only rider I ever saw use this particular technique.