If the logistics can be worked out an aluminum casting is a great suggestion. As Joe said, it could even be polished to resemble a chrome finish. Come to think of it, it would make perfect sense that the original might have been made of cast aluminum to begin with, which would have been both economical and practical when the car was originally built.
Hope you're able to get the unit cost down to something near reasonable. And it's also an excellent idea to include a reproduction stamp on the backside of each piece cast.