As others have said, best you can do is bead blast and scuff up. I have two - a Cimarron (Uberti) and USFA Rodeo - done up after the fact. But, as said, they had originally been blued. The Cimarron was actually done for me by the smith at Cimarron on this side of the pond as they didn't have any of the "Original" (old west) finish in my caliber (.44 Sp) in their shipment order at the time and I was impatient. Through my LGS that was friendly with them, they offered to "do" a blued Model P they were inspecting on the bench. The USFA I had done by my smith.
Cimarron top, USFA bottom, 4th (late 3rd( Gen Colt in the middle.
Another of the Cimarron
Back to the stainless, there may be some "acid etching" I'm not aware of, but I say no, don't go there. I'd get a blue'd one to 'speriment with (there are formulas in threads in several of these forums, often involving vinegar, sometimes naval jelly to strip, etc.)
About Rugers, it's my understanding the underlying "in the white" steel on blued guns is brighter than other brands, this according to my smith, so results may be different. Not sure I've seen a blued Ruger "antiqued." Would be interesting. The current (New Vaquero) crop is nothing special to look at with it's plain blue (black) finish, so it's tempting to mess with. I'll post if I get the itch!