I converted my Betstco flail mower to fit my harbor freight quick hitch by drilling new holes for the 3 point attach brackets when I first assembled the mower. Pretty straighforward except it left some extra unused holes in the deck. Unfortunately, the PTO shaft was too short to fill the extra 4 inches- I tried it anyway, but it came apart when I tried to mow. (big excitement!)
So if you decide to align your 3 point mount on the mower to match a quick hitch, be advised you will likely need a longer PTO shaft to make it work.
I just take my quick hitch off when I mount my mower.