Now, I have a 22/45 67/8 GC and have mounted a Tasco PDP3 (5MOA dot size, 11 brightness settings) onto a Weaver mount made for the 22.45 from Clark Custom Guns. This set-up has worked well and I have enjoyed it. The mount uses the 3 holes nearest the barrel-end and allows the retention of the rear sight so you can de-mount the dot and shoot iron sights (like when your batteries fails and you have no spares). Remount of dot maintains zero rather well IMHO. Once you shoot a dot, particularly if you need vision correction, I do not think you will go back to iron.
I am looking to mount a dot on my new AK47 as the sight picture for my eyes with the iron sights is not too good (but I can still group enough to put on a big hurt!) I just found a new-in-box PDP3 at Dick's Sporting Goods for only $39...paid $59 a year ago for my first PDP3 and that was a bargain at the time.