I'm working on a '37 Buick and replaced the single reservoir MC with a dual reservoir MC. In order to do this I had to move the MC to the other side of the X crossmember which made the MC difficult to get to. I checked out remote reservoirs, and like you thought the plastic ones offered didn't fit the look of the car. I searched the net and found a site for race cars that had a post about remote reservoirs.



You can fine these on eBay if you search for "metal bottle"

You would need to drill a vent hole in the top and install a diaphragm gasket under the cap to allow for level changes in the can. You can find the gasket at any auto parts store.



According to the site where I found the first image, there is some European vintage car that uses this set up and charges a small fortune for a reproduction kit that uses the same cans. I have the cans but haven't installed them yet. I still need to figure out how the tap into the bottom and seal them but that can't be too much of a problem once I get to it.