They do not make a front sight arrangement like you talked about.
And if they did, the sight on the receiver would be so close that you would be basicly still pointing the rifle.
It would be like having pistol sights on your rifle.
But a front sight Ramp could be fitted that uses a Set Screw to hold it on the barrel.
It would be a Band Type sold by Brownells, but you have to find one that fits your barrel, unless the Ruger front ramps are a Band style.
You are still looking at having some kind of gunsmith work done, unless you are pretty crafty