You can check the intake part number and carb application if you wish. The carbs are a little harder to identify. Someone else can help you I'm sure. You can also check the casting dates, but if the block vin and the casting/part numbers are correct, they are probably the correct parts. If you find a nonoriginal intake or carb, you can eventually find the correct part so don't let that kill the deal if you really like the car.
Also, the intake part number for the 68 400 Firebird changed at mid-year. I'm unsure if the GTO's did or not. But if something looks incorrect, don't jump to conclusions. I was confused about the intake part number for a while before I bought my car since most parts lists did not list the second intake part number.
Post more questions when you have them. Good luck!
