I just installed a fiberglass hood and had a lot of "fun" with those hinges. With the hood laying right side up you want the top of the hinge just slightly below the recessed area on the hood. Maybe 1/8 to 1/4" below. You don't want any of the hinge sitting above the hood. It also helps to look at the hinges on the stock hood if you have it. You can always ream the 2 mounting holes open to allow the hood to drop more.
Oh and don't let your slightly intoxicated brother-in-law handle one side while you do the other. Same person does both!!