I can't remember all of the frame/slide combos he recommended but I do remember Fusion was one of the many. Allen is good at finding parts also, he helped me find a pic rail mount for my Trailside pistol, it had been unobtainium for me to find. I won't have to alter anything on it now to get a RDS mounted.I have a Fusion frame and slide build that came out well.
As I’ve casually looked lately, availability is not good for parts though.