I missed the question about the notch in hte keel for the cable, ours had it, but some boats came with the tip of the keel cut off and a Stainless-Steel hook in it's place.... I remember seeing at least 1 or 2 like that on display at the New England Boat show in the early 1970's. However, I've never seen one since!
We modified our keel about 2 years before we sold her after the boatyard tried to winch
the keel up flush and snapped the tip of the keel off (Luckily with the boat on hte cradle? so the keel couldn't drop far!).
You can count me as one who will back up the need to be ABSOLUTELY sure that the cable is well seated in that notch before raising the keel too far. We ultimately just hooked the cable on each Fall before haulout, raised the keel just enough to remove the locking bolt and instructed the yard to raise the keel after they hauled us on hte travel-lift.