I don't know of anybody that makes a one piece rail for the Ruger rifles , I know that Burris used to make a weaver conversion that mounted to the Ruger base and they had 3 or 4 slots in them.
Its should be a bit lower as the front is the full round diameter and the rear is semi-flat. they could be close though.
I've been pondering the full flat base for my Sako and just drilling and tapping it. The whole dovetail thing kinda sucks since their not consistant from model to model