Dan,
For any top quality reproduction plates check out www.vintagebrassplates.co.uk
Talk to Chris he does a fantastic job and offers all styles of Wallis and M-H plates,he can reproduce any plate from a good photograph and measurements, so you don't have to part with your original. Brass or aluminium he does them all and he does ship to the US, but over the years I have carried several plates across for Massey Collectors.
If you can't get hold of him direct I have one here if you want it, check out his quality first on the website.
Malcolm.
www.vintagebrassplates.co.uk