I do not, but I'm pretty sure you won't need the biggest one available. Your FG hub is basically an FW with dynohub. I have an FW on my 1950 Norman Rapide, so I know that gearing pretty well. When I got the bike one of the first modifications I made was to switch the sprocket to a 22, but one ride told me that was too big; with a 22 I could get up most hills in L, and rarely needed B at all. I switched it to a 20, I think, and found that to be about right, though I may switch to a 19 one of these days. Now, your bike is definitely heavier than mine, but your wheels are also smaller. So though you may well want a bigger sprocket than I'm using, I don't think you'll need a 22. I'm guessing a 20 will suit you fine. Get two or three of the cheapest ones you can find --you can get them for $2 or $3-- and experiment.