Hood Scoop Help

I just got a set of original Dart GT hood scoops that I'm going to put on my 71 Scamp. I'm looking for help in were exactly I should position them and how large of holes I should cut. I've only seen pictures of the underside of a hood with these scoops and it looks like their round holes aproximately 5-6 inch in diameter with a rubber gromet on each one. Does anyone know were I can get gromets for the holes? How about the size of the holes? details, details....

Thanks in advance for any help!