Please don't use rivets as they will eventually loosen and telegraph their location around the hood scoop. Use a 3M panel adhesive and bond the scoop to the hood. Lightly grind the scoop and hood mating surfaces before applying the panel adhesive.
Note: If you have to clamp the scoop to the hood to get a better fit it will take some creativity if you lack the proper clamps. Sometimes you can get away with duct tape to hold the scoop in place while the bonding adhesive sets.
Use a good quality filler and block sand after application of filler as deemed necessary.
A high build polyurethane filler primer should be used after the leveling process has been completed.