Tom....
If you can point me toward an Airbox, I can get it duplicated. Between doing some of the work myself and working with several of the machine shops locally I can get pretty much anything fabricated. Where I live there are about 20 professional race teams within 20 miles.... lots of fabrication talent about.
HAving a factory box to use for patterns and specs would be the ticket. Im not positive I would duplicate it 100% though. I know clearance over the radiator is extremely minimal and having a square section box going over the radiator that has very little "give" can easily result in a dented hood. I would probably prefer a rounded section snout on the airbox to go over the radiator so it could bent some and prevent any hood issues.
Anyway, let me know your thoughts on getting an airbox to start from.
Terry