All 68 BB's were SS. To determine the RS option you should have the wiring, firewall and radiator support RS holes, RS tail lights, etc... check the AIM to determine the RS details. You should have a BB cross member if Munice 4 spd, all 68 BB came with 12 bolt posi rear axle, SS hood springs, power brakes, rear pressure brake regulator, dual exhaust brackets, the muncie 4 spd hole and clips, etc...
What do you have for a fan? Carb? throttle linkage? Do you have factory gauges? if yes what red line RPM is on the tach? what wheels do you have? Feel free to ask me questions...