Any picatinny rail drilled to fit the Remington. Rings to fit the scope, as long as they're made to fit on a picatinny rail any will work as long as they fit the scope.
I suspect on the rings he was hoping to hear low, medium, or high for clearance.
A 50mm is fairly tall, but with the rail, I suspect you can get by with medium and possibly even low. I think there are sources online that can tell you which you need-you might even try Leupold, see if they have a chat or a hotline.