The US Body link only has a GT500 molded scoop in their tilt front, that would make changing plugs easier
. It almost looks like a cowl induction from the picture or you could open the front of the scoop, either way its a big project. The second link doesn't show the late '70's hood with the scoop, I'll ring him tomorrow (holiday today) and find out if the molds are still around and cost. He had a cobra jet style scoop molded for one and maybe a cowl induction but I'll check.
As to using a scoop or hood, I guess my concern is how you cut the hood and support it. Not being a body person (autobody), you'll have to make that call. Dave looks like he did a great job. I've read pro's and con's to molding in scoops and not getting cracking.
The inlets for the ram-air box you see in the pic are 5" pipe welded to the rad saddle. I wanted a little more meat when putting the ducting on and off. I use a flat base on the air cleaner (gave more room for plumbing and linkage), the air filter element is a 14" x 5". With the Performer RPM at 4.12", a 1" carb spacer, carb, and 5" high filter element I've got about another 1" to 1 1/2" clearance to the hood.
Hope this helps.
PS - Dave, could post or e-mail a couple pics of how you cut your hood under the scoop. Thanks