Yes, Micro sight made a fully adjustable rear sight to fit a dovetail for universal applications. I have seen your model Ruger with this sight. They also made one for universal applications that screwed to the top frame of the gun. Although this is not what you're looking for it can be used as you wish by simply having it soldered to a dovetail filler blank of a size fitting your gun, and discarding the screws.
Recognize these are no longer made but anything can be found on the internet auctions or by listing your 'wants' in the classifieds on this forum.
You will need a taller front sight however which will be a bit more permanent. If that's not an issue, a Ruger Super single six front sight is the easiest as it requires only one drilled and tapped hole but your original blade front sight would have to go.
To avoid the front sight change and if you're a little handy you could adapt one of these sights using the dovetail blank method above. By trimming the top of the blade, deepening the notch and trimming the underside of the sight before soldering to the dovetail blank, which would eliminate the windage adjustment feature (but OK since you have the ability to tap the sight back and forth in the dovetail for windage), you could probably mount it low enough to be able to retain your original front sight blade.