There are a few ways to re-bed and none of them, for me, would involve only epoxy. Fin keels move and flex regardless of how you attach them. Epoxy it on and it will still move or flex some and the epoxy has nearly ZERO elongation before break sio it will fail.
The best method I've seen is to mix an epoxy butter and then heavily wax the lead keel & bolts, or better yet grease the bolts. Drop the boat onto the keel and epoxy butter, let it cure lift boat off. Now you have a nicely matched hull to keel joint. You can also do it in reverse but I prefer the bond of epoxy to fiberglass as opposed to epoxy to lead for the epoxy butter mixture though eitehr is probably fine.
Next you take a Dremel tool and cut a shallow v-groove into the top of the lead face of the keel that meets the hull. A laminate trimmer and edge guide with v-bit works better if the keel is wide enough for it to fit. Go all the way around the keel about 3/8 to 1/2" in from the outer edge until you complete a circle and the v-groove joins its self. Now apply a marine sealant, I like Sikaflex but 5200 is also good (but very permanent and it may rip the epoxy butter off on the next round) as is 4200, and drop the boat back down. The v-groove makes a nice thick gasket that can absorb lots more flexing than no thickness or minimal thickness. A 1/8" thick bead of 5200 will stretch and move a LOT more than 1/64th of an inch of sealant before a failure.
Most all builders DO NOT take the time to make a "gasket groove" or to "butter match" the hull to the shape of the keel. It involves a LOT more time than builders are willing to exert or spend time/$$ on.
Please for your own sake do not solely use epoxy. You need some allowable movement as the forces on a fin keel are tremendous and I've yet to see one that did not move some. Any movement with epoxy will mean failure and adding stuff to to to make it more flexible is not enough. Just because a fairing compound has cracked due to movement does not mean the marine sealant between the hull and keel has..
Here's a link to a good description though they did not cut a sealant/gasket groove..
Keel re-bed (LINK)