Ive heard some of the fiberglass hoods can warp. Some are sold w a metal underside to stop that. I got my shelby trunk lid and had to take out the lift supports it was bending the trunk. For the hood i got a bolt on scoop. dunno about stuff from either, I got my stuff from kar mustang
I have Maier hood and Shelby nose on my fastback. Depending on how picky you are, you can easily spend more than the hood making it right. They don't fit for squat but can be fixed. Learn how to work with fiberglass and you can do it yourself for about $50, which is what I did.
Find out what resin they use ,if it is ORTHO say no ,ISO is what you want . ORTHO will warp with heat ,and it will bow ,usually after painted ,ISO resin is used in marine aplication and will not give you problems after painting
I tried using the heat method to get my Maier hood into some semblance of shape. I put over 80lbs of weight on it, plus two big cabinet clamps and enough heat that you couldn't put your hand on it and left it for several days with zero affect. Not that it mattered, not only was the hood bowed in the middle, as are ALL Maier hoods, but it was so narrow you could see the fender bolts underneath. All the heat in the world won't fix that. I fixed it in about an hour by cutting the skin loose from the subframe, setting the shape how I wanted, then 'glassing it back together. To widen it, I just sanded through the gel coat, then laminated on strips of 'glass matte. The fit is now perfect and it cost about $50. I've seen body shops charge upwards of $1200 to fix fiberglass because like most people they make you think it's magic. It's not. If you can operate scissors and a mixing stick you can do it.