To the best of my knowledge all the 455 variations used the 11mm dovetail. The model 452 used both the 3/8" and the 11mm dovetail depending on which variation you ended up with. I've not used any plates but both DIP and AREA 419 make them. I have a 455 Full Stock that has open sights, with a 2-7 scope in either Leupold or Burris medium rings you can see the front sight ghosting when the scope is in lower powers. You'd have to go some what taller to get above the sights. But I like to keep my scopes as low as possible and consider the front sight ghosting to be a non issue.