The PA State Troopers used to carry 6" Security Six's in stainless back in the late 1970's,IIRC, the last revolvers they were issued.
I have owned 4 of them over the years,4" and 6", as well as a Speed Six. They are my favorite Ruger revolvers, but they are long out of production. If you have knowledge of revolvers, and check it over to your satisfaction, I can't imagine you would go wrong with it. They were way way overbuilt, and they generally took 20 years of regular shooting before they were broken in from new. I don't see many for sale recently-I assume most owners want to keep them. They are very accurate reliable revolvers, and the 2 peoblems I can think of are -the very old models have a unique grip strap shape and there are NO replacement grips for them. AND- the design of the grip transmits lots of force back to the shooter...The GP 100 replaced the SS's and many think they were a great improvement...then again, many do not.
ADDED- For $280, you stole it-congratulations! It is built like a dump truck, and a really great revolver.
mark