First, the lifesling rigging really is best handled by a halyard that will bring the "victim" up into the cockpit; and, can be rigged and controlled from the cockpit. I think that a boom end fitting with the very effective multi-part block and tackle system would make the most sense. A halyard from the masthead will be too tough (or at least a lot tougher) to get the person back into the boat.

To get a dink back on the boat on the foredeck, I prefer to use a spinaker halyard. If you need to, I'd use the Lifesling block and tackle by putting the halyard fitting high-enough so you can effectively use it.

If you want to pull an outboard back onto the boat -- I think it depends whether you can handle moving the engine around the vessel. (A 4-cyle engine is pretty heavy ;^) Then I think you have to figure-out a purchase system that works in a location that will bring the engine back where you can use it.