So they altered an existing last for you? If so sounds like you should stick with that and just alter a bit further either through Kolecho or your previous contact. If you choose a new last the F could be good. To be honest, in a size 47 / 13 I would seriously consider the 3636 last. It has a classic shape with a high instep and in a size that big I imagine it would look quite elegant. Something to contemplate.