You'll have to be a little more specific about the location and shape of the cut out you're referring to.
As far as I remember all vintage ACP cylinders are the same including the old models.
But no, no factory Ruger ACP convertible cylinders were ever cut for clips. The cylinder has to be removed from the gun to use and load rounds that are in clips. And the rear face of the cylinder has to be machined (faced off) about .015" to make space for the clips.
However, some have machined the cyl and used clipped ACP ammo in a 2nd cyl for a rapid reload for self defense scenarios by swapping out an extra cyl from a belt pouch.