I've now finished the trumpeter master figure as well. I was able to re-use the original legs and saddle from the Hussar figure as they survived relatively intact from the previous master mould. (You can see the "donated parts" in the photos, as the moulding process dyes the greenstuff darker). The upper torso etc is all new however.
I'm planning a couple of officer conversions of the basic hussar (which should be more straightforward than this figure). After I've done that they'll all be going into a production mould.