The originals I have seen have a small square base with a small blade on top. It's pretty ugly. I just soft solder a brass blade on, I don't cut a notch for it, Original barrels are incredibly thin at the muzzle, it wouldn't take much to dent the bore. None of my blades have ever came off, that I know of.
I have never seen an original with a dove tailed front sight, there just isn't enough barrel wall to do it. Barrel wall is something less than 1/16".