Nobody, not even Ralph Lauren, is offering chesterfield coats with that silhouette, and those dimensions, off-the-rack these days. Your best bet is to have one custom made, or to look on eBay and Etsy. http://mattdeckard.com/ could probably create one for you.
This vintage 1930s or '40s coat by "Rogers Peet" (see photo) sold a few months ago on Etsy for over $500, I believe. How much are you willing to spend?