An easy way to tell a original hood from a repop is, Look at the rear corners of the hood where it meets the cowl and fenders. With the hood open,On a GM hood there is a little kick down or notch in the metal. On a repop there is just a 45 degree angle in the metal. This may sound confusing but if you look at the hoods you can spot the differance from 20' away.
GM HOOD BELOW:
No cowl induction hoods installed on a Camaro until the beginning of January. Yes there is a very late December built ZL1 Camaro with one, but I would say that is a special case. Notice to dealers of the options existance didn't go out until Thanksgiving of 68.