Re: Installing Additional Keel Bolts
Rarely is it justified to install additional keel bolts. And other than on high end racing boats I have never seen a reason. While they may look it, keels are not just slabs of lead bolted to the bottom of boats, they are highly engineered items, with a great deal of thought and work by engineers to figure out how many bolts there should be, and where they should go. Adding new ones is rarely going to add any more safety, and may weeken the entire structure.
For instance, have you considered how the new bolts are going to be bolted to the boat? Is there sufficient structual support there to take the potential loads? If not you could over stress a non-reinforced section of the hull quickly.
Bolts are typically spaces far enough away that their compression loads don't merge. Adding new ones can screw up this careful placement, and create peak loads beyond the safety margins.
Finally as to your method... It would work, for some definition of work. But no i wouldn't consider it sufficient. Lead is very soft, and can't take much sheer load. This is exacally why keel bolts aren't just tapped into the keel. The J shape is is increase the area of load distribution, and to put some of the lead in to compression, as opposed to tension. What you suggest could work, but would require some real engineering to figure out how large the hole would need to be to provide sufficient bonding area to support the loads you would face.
In short, I see this as a lot of work and cost, for minimal if any gain, and a real possibility of damaging the boat for no identifiable reason.