Thread re: Dual Master Cylinder Conversion ('65 w/power brakes)?

Plumb the rear circuit direct from the MC, but needs an inline adjustable proportioning valve ($30 ebay). Adjust so the fronts skid just before the rears in a wet parking lot.

Just wondering why the suggestion to adjust the proportioning valve to lock up the front wheels first? When the front wheels lock up, one loses all steering control, so I was wondering about that. I would think it safer to lock up the rear wheels just a tad sooner? I'm no brake/physics expert though.