I replaced the front sight on my 1894 Marlin 45LC with one of their firesight posts. I like it. Can't speak to the rear sight referenced. I do like the adjustable peep sight that I use, though. Never had a problems with William's sights.
“There are three reasons to own a gun. To protect yourself and your family, to hunt dangerous and delicious animals, and to keep the King of England out of your face.” - Krusty the Clown