Is the Ruger one of those with the flat action ? I'm trying to think which are similar ? I know my TC Icon is also flat on the bottom.
OK, found a picture
Based on the image above, it looks like a 3 pillar bedding job would be the best. The recoil lug does not look very big, so I would recommend either chopped fiberglass or carbon fiber as filler in that area. You want something really strong and hard.