Sorry for the late response, not sure how much help I can be, because my setup is different.
I have a couple 457 rifles, including a beautiful Lux. I chose to keep it open sights, but initially I did have a 3-9 with a 40mm objective on her, using Leupold 11mm high rings. I did have to remove the rear sight (very easy to do) to have enough clearance. Any higher I went would be too high to get a good view. Because you have a smaller objective you may be able to use medium.
Any decent gun shop, including Cabelas, would set up the right size rings for you if you bring the rifle in. I recognize it is a PITA but saves some running around.
I eventually chose to go scopeless on my Lux, shooting open sights is a bit of a dying art these days with my kids. Everyone wants to shoot with scopes, but we have loved shooting that rifle with their very accurate open sights. Reminds me of my k98 somewhat.
Good luck, beautiful rifle.