One question: Would the front and rear header panels from a '76-'78 or a '74, '75 Imp. work on a '74, ''75 New Yorker?
I've seen it done.
Yep, it can bolt up. But you need the corresponding hood to go with it because the hump or center crease in the 76-78 NY'er hood rises higher than the 74-75 NY'er/ Newport hood. Now the 74-75 Imperial header and hood has the same characteristics and height as the 76-78 NY'ers except the hood ornament assembly is different on the Imps.
74-75 Imps and 76-78 NY'ers has a "Y" stamped in the front lip of the hood. 74-75 NY'ers/Newport's and 76-78 Newport's have a "C" stamped on the front lip of the hood.