Traditionally what I've seen done is a lip protrudes from the forend much like you could make when installing a cast nosecap. The ebony is carved away to fit over the lip, then glued with hide glue as they did with horn nosecaps. That way you get lengthwise grain gluing surface instead of a butt joint, without messing about with drills and nails. Though the nails are plenty strong, I worry about the wood cracking with age. Titebond 3 or dyed epoxy works well these days instead of hide glue, though fresh hide glue is darn strong stuff.
-Eric