Where can I buy designer mens shoes and clothing for the big and tall?

I am christmas shopping for my fiance and he is 6'10 but athletically built. He loves designer and I am looking to buy him some Gucci, LV, Prada, etc this holiday season. He wears a 16-17 in shoe size and about a 3X-4X in clothing. Can anyone tell me a good website to find these AUTHENTIC items or even a store, we live in ATL. Thanks in advance!!!