Simply-- an RS/SS was just an SS car with the RS option. The RS package was an appearance option only--it included hideaway headlights and different trim and taillights and backup lights etc... It also had RS emblems--EXCEPT on an SS car. The SS package always overrode the RS badging, so, no SS cars had RS emblems. The SS cars only came with two basic engine options--a 350 small-block or a 396. So if the car has a factory 327, it isn't an SS. All SS cars had 12-bolts as well. If the car has a 10-bolt and a 327 that's a sure indicator it wasn't a factory SS car.
It easy enough to see if it came factory with a vinyl top--just look inside the trunk were the 1/4-panels meet the roof sail panels and under the tulip panel below the rear glass. Vinyl top cars had holes drilled for the trim clips. If the holes have been filled, the car had a factory vinyl top. If there are no signs of trim clip holes, it didn't unless the sheetmetal has been replaced.
Hope this helps!