HI... Average Joe's posted picture from http://www.nycsubway.org shows a perfect example of the SIRT trains. On the website there are a bunch of historical photos of the SIRT through SIRTOA (Operating Authority-when NYC took over operations from the Baltimore & Ohio RR) and SIR. The Long Island RR Owl cars were loaned to the SIRT around 1973 (that's when I rode one while on leave from the US Air Force). I don't know how many sets were loaned.
As far as Staten Island being the forgotten borough, when I was growning up there in the 50's to 1971; yes it was a forgotten borough. We would get hand me down buses from Brooklyn, especially the MACK buses (6000 numbering series) and very early GMC (9000 numbering series). In fact, when I was growing up on SI; the Staten Island Mall was an airstrip. There was farmland and even a dairy near Tottenville. So before the Verrazano Narrows Bridge, Staten Island WAS the forgotton borough.