Heels at Shoulder Width with Toes SLIGHTLY Pointing Out, would be ideal for High Bar Back Squats.
Note that Back Angle (the angle that your Back Makes with the Ground) is going to be a bit more Vertical than would be for a typical Low Bar Back Squat. Also, Back Angle for a Front Squat would be even more Vertical (almost Straight) than for a High Bar Back Squat.
Make sure to Break both at the Hips and at the Knees, at the same time. Make sure to track your knees over your toes.
High Bar Back Squats use the Quads much more than they would your Hamstrings.
The Front Squat might be an Even Better Exercise, if you are looking to work the Quads more than anything else.
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