Our boat has an encapsulated lead keel. Yes she was built that way at the factory. I was thinking a few layers of S-glass and epoxy would keep the water out and keel on. Since you have those layers of glass holding the keel on why would you need bolts? Pretty sure one would have to remove the gelcoat around the hull were the keel attaches so one could bond to the glass.
With all due respect, its not that simple. To begin with, there are two ways this can be done. It can either be done as a non-structural sealer encapsulation or as a structural encapsulation. If you are talking about applying a few layers of S-glass and epoxy, in order to keep the water out, then that would be a sealer approach to encapsulation. It might stop the water but it would lack the structural strength to actually support the ballast keel. In that case, the boat would still be dependent on the keel bolts as the structural support for the ballast keel. That is why others have mentioned the issue of crevice corrosion of the keel bolts if the OP chose to simply apply a sealer encapsulation.
The second way to look at this would be to create the structural equivalent to the encapsulation envelope like yours and that might be found on a boat that was molded with an encapsulated keel. To do that the encapsulation would need to be a lot more than simply a few layers of S glass. It would by necessity need to be somewhere between 1/2" to 3/8" thick to develop the necessary strength to totally support the weight of the ballast keel on a boat of this size, with a leading, bottom, and trailing edge thickness closer to 3/4 to 1" thick. In order to form a structural bond the full thickness of glass would need to overlap the hull by 12 to 18 inches with the cloth tapering out over another foot or so. One thing that complicates that on this particular boat is that the propeller shaft exits through the back of the keel stub limiting the amount of overlap that can be gotten between the new and old glass.
To lay up that much glass efficiently, cost effectively, and reliably, ideally the boat would be placed in a rotating cradle so that would allow the boat to be rotated so that the keel on either side is nearly horizontal. That potentially means removing the rig and engine.
And whether the encapsulation is structural or simply a water seal, once the glass is laid up, the new glass on the hull and keel would need to be refaired and the fairing material sealed. In either case it is a huge job compared to simply replacing the keel bolts.
I hope that clarifies what is involved,