I don't have the bonnet at my new home yet. I installed the pins into the slam panel top with double nuts above and below. Then I marked where the pins touched the bonnet and drilled a guide hole. Then I used a dremel with a cutting disc to cut a shape into the top layer of the bonnet, followed by the dremel with a grinding bit to finish the shape to fit snugly. There's still a margin for error that the aerocatches allow, and you and bend and twist the top of the pins to meet the catches. I drilled holes from below just big enough to fit a socket bit to secure the nuts for the catches from below.
The direction that the catches faces is cosmetic, but be aware that the shape of the hood and the placement of the pins obviously needs to take into consideration that they need a relatively flat surface to be bolted into.
No pics except my words...and your imagination...so infinite pics, though maybe not the right ones, but you get the idea