I had a similar thought myself after remembering doing something like this as a teenager on an old honda engine in a go kart, my mates dad helped me out, he built vintage racing Austin Seven's for a living. I do have a couple of potential candidates to do such a job so it can go on the further investigation needed list.
Cant decide if a 32mm carb is too big or just get a 30 like the one you pointed out. There are KOSO 32's (Keihin clone) on ebay uk for a good price, not sure if a chinky carb is the way to go though hmmm!
