55 Last: 9.5EEUS Men's Brannock: 10EEE
I watched several of Frank's youtube videos, Facebook forum recommendations, and I lucked out finding a retail store where I could try on some whites in a 55 last, and discovered I could go down a full size from my normal shoes.
I ended up in the 9.5EE, but I could probably do a 9.5 EEE or have a wider toe shape, but they will work. I'm accustomed to poor fitting shoes because I have duck feet with a long second toe. I'm a 10EEE in Brannock. Wear 10.5 in Vans Old Skool, and 10.5 E in most shoes.