How can you tell if a car is a Rally Sport

[mas90241]

I bought a rolling Z/28 shell with a crossram even after some very intelligent people told me it was not a good idea. The car has no front end sheet metal,dash carrier asm,windsheild wiper or washer. Is there any way to tell if a car is an original rally sport? The rear valance panel has the reverse light holes but I was told that the car was going to be converted to a R/S and the square hole that the light fits into does not look like a factory cut. But there is always a possibility that the panel was replaced in the past and this was cut in at a body shop. It seems to me that towards the end of when GM had sheet metal being sold through the dealers, they superseded the part to a non R/S panal. Are there additional holes stamped in the firewall that would give me a clue?