Blue Force Gear's sling hardware has a few options.
The A2 Buttstock adaptor would be a start, I can't tell from the pics of the Ruger if the Universal Wire Loop will pinch small enough to go thru at the front. Alternatively you could try the Rail Mounted Fixed Loop. I've not used a sling mounted to the underside of the rifle so I don't know how the rifle will hang on a two point sling but I'm sure it's something you'd learn to use. For the quick detach option there's the MASH Hook or Sling Snap Hook attached to the D ring on the A2 buttstock adaptor.
Just add your preferred 2 point sling.